This document proposes techniques for embedding unique codewords in electronic documents to discourage illicit copying and distribution. It describes three coding methods - line-shift coding, word-shift coding, and feature coding - that alter document formatting or text elements in subtle, hard-to-detect ways. Experimental results show the line-shift coding method can reliably decode documents even after photocopying, enabling identification of the intended recipient. The techniques aim to make unauthorized distribution at least as difficult as obtaining documents legitimately from the publisher.
This document summarizes and compares entropy and dictionary-based techniques for lossless data compression. It discusses how entropy coding like Huffman coding assigns shorter codes to more frequent symbols, making it well-suited for JPEG images. Dictionary techniques like LZW replace strings with codes, performing better on files with repetitive data like TIFFs. While entropy coding has simpler encoding, dictionary methods have better compression ratios and decoding capability. The document also presents the proposed Huffman coding of a bitmap image to assign variable-length codes based on color probabilities.
A zero text watermarking algorithm based on the probabilistic patternsIAEME Publication
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The document summarizes a research paper that proposes a new zero-watermarking technique for digital text documents. The technique utilizes probabilistic patterns in the text based on a first-order Markov model. It constructs a transition probability matrix to represent the probabilistic features of the text. This matrix is then used to generate a watermark key, which can later be extracted and matched to authenticate the text or detect tampering. The technique does not modify the original text document. Experimental results show the approach can accurately detect random tampering attacks in text documents.
Hybrid zero watermarking and markov model of word mechanism and order-2-3IAEME Publication
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The document discusses a hybrid zero-watermarking and Markov model technique for content authentication of English text documents. It proposes using a second-order Markov model at the word level to analyze text and generate a watermark. This watermark is then embedded using a zero-watermarking approach that does not modify the original text content. Experiments on six datasets of varying lengths show the approach is more sensitive to tampering attacks and has good accuracy for tamper detection compared to other recent approaches. However, it is not effective against reorder attacks on large documents.
IRJET-Market Basket Analysis based on Frequent Itemset MiningIRJET Journal
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The document reviews various techniques for compressing scanned handwritten documents in Devnagari script, as digital libraries are increasingly storing documents which require large storage space. It discusses prior work on compressing printed and handwritten documents in other languages as well as techniques specific to Devnagari script. The review concludes that compression techniques are important for archiving and transmitting handwritten documents in Devnagari script given the need to preserve large volumes of historical documents in Indian languages.
Lights and Drums: an Unplugged-style ActivityGeorge Boukeas
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Summary: In this unplugged-style activity, each group will transmit a message to the other groups, using a different code (known to the recipients) and a different communication medium. The aim is to familiarize the participants with the concept of information representation and especially digital binary representation. At the same time, the part of the activity pertaining to message transmission introduces important issues regarding the role of symbols in each code, as well as the role of the physical carrier used for transmitting or storing information.
Goals: Associate representations that employ the symbols 0 and 1 with other, more familiar, binary representations, thus establishing a view of the former as yet another binary representation. Highlight the physical form of information in the systems that transmit, store or process this information.
Duration: at least 30 minutes
1. The document presents a novel approach to text steganography that hides secret messages in null spaces of cover text documents.
2. The approach encodes secret message bits as extra null spaces inserted into the cover text plaintext, with one null space representing a 0 bit and two null spaces representing a 1 bit.
3. The encoding is done by a hiding program that generates a stego text file, while an extractor program can recover the secret message from the stego text. The approach aims to covertly communicate secret messages within innocuous-looking text.
Drubbing an Audio Messages inside a Digital Image Using (ELSB) MethodIOSRJECE
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It is mainly focused today to transfer the messages secretly between two communication parties. The message from the sender to receiver should be kept secret so that the information should not known by anyone. Secret is the important thing today. The technique that is used for secure communication is called as steganography and it means that to hide secret information into innocent data. Digital images are ideal for hiding secret information. An image containing a secret message is called a cover image. In this paper will discuss about secret transformation of audio messages. The audio messages are hidden inside a cover image so no one can hack the audio but the audio should be encrypted before hidden inside the image
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
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This document proposes a new compression technique for Gujarati text based on a dictionary approach. It compares the proposed technique to Huffman compression coding. The proposed technique compresses Gujarati text to 60% by using a lossless Unicode-based compression method that assigns unique index numbers to characters in a Gujarati dictionary and concatenates the numbers for adjacent characters. An evaluation on sample text files shows the proposed technique achieves an average compression ratio of 60.61% compared to 53.20% for Huffman coding, representing a 7.41% improvement in file size compression.
This document summarizes and compares entropy and dictionary-based techniques for lossless data compression. It discusses how entropy coding like Huffman coding assigns shorter codes to more frequent symbols, making it well-suited for JPEG images. Dictionary techniques like LZW replace strings with codes, performing better on files with repetitive data like TIFFs. While entropy coding has simpler encoding, dictionary methods have better compression ratios and decoding capability. The document also presents the proposed Huffman coding of a bitmap image to assign variable-length codes based on color probabilities.
A zero text watermarking algorithm based on the probabilistic patternsIAEME Publication
Â
The document summarizes a research paper that proposes a new zero-watermarking technique for digital text documents. The technique utilizes probabilistic patterns in the text based on a first-order Markov model. It constructs a transition probability matrix to represent the probabilistic features of the text. This matrix is then used to generate a watermark key, which can later be extracted and matched to authenticate the text or detect tampering. The technique does not modify the original text document. Experimental results show the approach can accurately detect random tampering attacks in text documents.
Hybrid zero watermarking and markov model of word mechanism and order-2-3IAEME Publication
Â
The document discusses a hybrid zero-watermarking and Markov model technique for content authentication of English text documents. It proposes using a second-order Markov model at the word level to analyze text and generate a watermark. This watermark is then embedded using a zero-watermarking approach that does not modify the original text content. Experiments on six datasets of varying lengths show the approach is more sensitive to tampering attacks and has good accuracy for tamper detection compared to other recent approaches. However, it is not effective against reorder attacks on large documents.
IRJET-Market Basket Analysis based on Frequent Itemset MiningIRJET Journal
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The document reviews various techniques for compressing scanned handwritten documents in Devnagari script, as digital libraries are increasingly storing documents which require large storage space. It discusses prior work on compressing printed and handwritten documents in other languages as well as techniques specific to Devnagari script. The review concludes that compression techniques are important for archiving and transmitting handwritten documents in Devnagari script given the need to preserve large volumes of historical documents in Indian languages.
Lights and Drums: an Unplugged-style ActivityGeorge Boukeas
Â
Summary: In this unplugged-style activity, each group will transmit a message to the other groups, using a different code (known to the recipients) and a different communication medium. The aim is to familiarize the participants with the concept of information representation and especially digital binary representation. At the same time, the part of the activity pertaining to message transmission introduces important issues regarding the role of symbols in each code, as well as the role of the physical carrier used for transmitting or storing information.
Goals: Associate representations that employ the symbols 0 and 1 with other, more familiar, binary representations, thus establishing a view of the former as yet another binary representation. Highlight the physical form of information in the systems that transmit, store or process this information.
Duration: at least 30 minutes
1. The document presents a novel approach to text steganography that hides secret messages in null spaces of cover text documents.
2. The approach encodes secret message bits as extra null spaces inserted into the cover text plaintext, with one null space representing a 0 bit and two null spaces representing a 1 bit.
3. The encoding is done by a hiding program that generates a stego text file, while an extractor program can recover the secret message from the stego text. The approach aims to covertly communicate secret messages within innocuous-looking text.
Drubbing an Audio Messages inside a Digital Image Using (ELSB) MethodIOSRJECE
Â
It is mainly focused today to transfer the messages secretly between two communication parties. The message from the sender to receiver should be kept secret so that the information should not known by anyone. Secret is the important thing today. The technique that is used for secure communication is called as steganography and it means that to hide secret information into innocent data. Digital images are ideal for hiding secret information. An image containing a secret message is called a cover image. In this paper will discuss about secret transformation of audio messages. The audio messages are hidden inside a cover image so no one can hack the audio but the audio should be encrypted before hidden inside the image
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
Â
This document proposes a new compression technique for Gujarati text based on a dictionary approach. It compares the proposed technique to Huffman compression coding. The proposed technique compresses Gujarati text to 60% by using a lossless Unicode-based compression method that assigns unique index numbers to characters in a Gujarati dictionary and concatenates the numbers for adjacent characters. An evaluation on sample text files shows the proposed technique achieves an average compression ratio of 60.61% compared to 53.20% for Huffman coding, representing a 7.41% improvement in file size compression.
Hiding Malicious Content in PDF Documentsdeathwing
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Proof-of-concept demonstration for a specific digital signatures vulnerability that shows the ineffectiveness of the WYSIWYS (What You See Is What You Sign) concept.
A Novel Steganography Technique that Embeds Security along with CompressionCSCJournals
Â
Problem faced by todayâs communicators is not only security but also the speed of communication. This paper provides a mechanism that increases the speed of communication by reducing the size of content; for this data compression method is used and security factor is added by using Steganography. Firstly, the focus has been made on Data Compression and Steganography. Finally, proposed technique has been discussed. In Proposed technique first data is compressed to reduce the size of the data and increase the data transfer rate. Thereafter on compressed data state table operation is applied to improve the security. Then, this is used as the input to the LSB technique of Steganography. At receiver end, firstly the LSB extraction technique is used, thereafter the state table operation in reverse form is applied and finally the original data is obtained. Hence our proposed technique is effective that can reduce data size, increase data transfer rate and provide the security during communication.
Text independent speaker identification system using average pitch and forman...ijitjournal
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The aim of this paper is to design a closed-set text-independent Speaker Identification system using average
pitch and speech features from formant analysis. The speech features represented by the speech signal are
potentially characterized by formant analysis (Power Spectral Density). In this paper we have designed two
methods: one for average pitch estimation based on Autocorrelation and other for formant analysis. The
average pitches of speech signals are calculated and employed with formant analysis. From the performance
comparison of the proposed method with some of the existing methods, it is evident that the designed
speaker identification system with the proposed method is superior to others.
TEXT STEGANOGRAPHIC APPROACHES: A COMPARISONIJNSA Journal
Â
This paper presents three novel approaches of text steganography. The first approach uses the theme of
missing letter puzzle where each character of message is hidden by missing one or more letters in a word
of cover. The average Jaro score was found to be 0.95 indicating closer similarity between cover and
stego file. The second approach hides a message in a wordlist where ASCII value of embedded character
determines length and starting letter of a word. The third approach conceals a message, without
degrading cover, by using start and end letter of words of the cover. For enhancing the security of secret
message, the message is scrambled using one-time pad scheme before being concealed and cipher text is
then concealed in cover. We also present an empirical comparison of the proposed approaches with some
of the popular text steganographic approaches and show that our approaches outperform the existing
approaches.
Improving the data recovery for short length LT codes IJECEIAES
Â
Luby Transform (LT) code is considered as an efficient erasure fountain code. The construction of the coded symbols is based on the formation of the degree distribution which played a significant role in ensuring a smooth decoding process. In this paper, we propose a new encoding scheme for LT code generation. This encoding presents a deterministic degree generation (DDG) with time hoping pattern which found to be suitable for the case of short data length where the well-known Robust Soliton Distribution (RSD) witnessed a severe performance degradation. It is shown via computer simulations that the proposed (DDG) has the lowest records for unrecovered data packets when compared to that using random degree distribution like RSD and non-uniform data selection (NUDS). The success interpreted in decreasing the overhead required for data recovery to the order of 25% for a data length of 32 packets.
Speech to text conversion for visually impaired person using Âĩ law compandingiosrjce
Â
The paper represents the overall design and implementation of DSP based speech recognition and
text conversion system. Speech is usually taken as a preferred mode of operation for human being, This paper
represent voice oriented command for converting into text. We intended to compute the entire speech processing
in real time. This involves simultaneously accepting the input from the user and using software filters to analyse
the data. The comparison was then to be established by using correlation and Âĩ law companding techniques. In
this paper, voice recognition is carried out using MATLAB. The voice command is a person independent. The
voice command is stored in the data base with the help of the function keys. The real time input speech received
is then processed in the speech recognition system where the required feature of the speech words are extracted,
filtered out and matched with the existing sample stored in the database. Then the required MATLAB processes
are done to convert the received data and into text form.
ADVANCED LSB TECHNIQUE FOR AUDIO STENOGRAPHYcsandit
Â
This work contributes to the multimedia security fields by given that more protected
steganography technique which ensures message confidentiality and integrity. An Advanced
Least Significant Bit (ALSB) technique is presented in order to meet audio steganography
requirements, which are imperceptibility, capacity, and robustness. An extensive evaluation
study was conducted measuring the performance of proposed NLSB algorithm. A set of factors
were measured and used during evaluation, this includes; Peak Signal to Noise Ratio (PSNR)
and Bit Error Rate. MP3 Audio files from five different audio generators were used during
evaluation. Results indicated that ALSB outperforms standard Least Significant Bit (SLSB)
technique. Moreover, ALSB can be embedding an utmost of 750 kb into MP3 file size less than 2
MB with 30db average achieving enhanced capacity capability.
The document describes the Huffman data compression algorithm. It was created in the 1950s by David Huffman to efficiently compress messages by assigning binary codes to characters based on their frequency, with more frequent characters getting shorter codes. This allows any message to be compressed in a lossless manner. The algorithm builds a binary tree from the character frequencies and reads codes from the tree to assign each character a unique code for compression.
Traid-bit embedding process on Arabic text steganography methodjournalBEEI
Â
The enormous development in the utilization of the Internet has driven by a continuous improvement in the region of security. The enhancement of the security embedded techniques is applied to save the intellectual property. There are numerous types of security mechanisms. Steganography is the art and science of concealing secret information inside a cover media such as image, audio, video and text, without drawing any suspicion to the eavesdropper. The text is ideal for steganography due to its ubiquity. There are many steganography embedded techniques used Arabic language to embed the hidden message in the cover text. Kashida, Shifting Point and Sharp-edges are the three Arabic steganography embedded techniques with high capacity. However, these three techniques have lack of performance to embed the hidden message into the cover text. This paper present about traid-bit method by integrating these three Arabic text steganography embedded techniques. It is an effective way to evaluate many embedded techniques at the same time, and introduced one solution for various cases.
The document proposes two techniques for hiding messages in digital images using steganography. The first technique encodes a secret message using punctuation marks before embedding it in an image. The second uses a modified scytale cipher to arrange the message bits in a grid that is then linearly embedded. Both techniques add an extra layer of protection on top of embedding in the image. Examples are provided demonstrating applying each technique using S-Tools software and analyzing the original versus stego-images.
This document summarizes an algorithm for hiding text within wave audio files. It begins by providing background on steganography and different techniques for embedding information, including within images, video, and audio files. It then describes the structure of digital audio files and how the least significant bit (LSB) manipulation technique works. The proposed algorithm embeds secret binary text into wave files by adding or subtracting a value from quantized phase coefficients of voiced audio blocks, depending on whether the secret bit is a 0 or 1. During extraction, the secret bits are reconstructed by determining whether the phase coefficient is greater than or less than the original quantized value. The algorithm is implemented in two phases - an embedding phase that hides the secret data in
We propose a model for carrying out deep learning based multimodal sentiment analysis. The MOUD dataset is taken for experimentation purposes. We developed two parallel text based and audio basedmodels and further, fused these heterogeneous feature maps taken from intermediate layers to complete thearchitecture. Performance measuresâAccuracy, precision, recall and F1-scoreâare observed to outperformthe existing models.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
HIDING A MESSAGE IN MP3 USING LSB WITH 1, 2, 3 AND 4 BITSIJCNCJournal
Â
This document summarizes a research paper that proposes a new steganography method for hiding text messages in MP3 audio files. The method randomly selects positions in the MP3 file to embed bits of the text message using the least significant bit (LSB) technique. The text message is embedded starting and ending with a unique signature or key. The methodology focuses on embedding one, two, three or four bits from the secret message into the MP3 file using LSB. The performance is evaluated based on robustness, imperceptibility and hiding capacity. Experimental results show the new method provides increased security compared to other LSB steganography methods.
IRJET - Hash Functions and its Security for SnagsIRJET Journal
Â
This document provides an overview of cryptographic hash functions, including their structure, properties, and selections in previous research projects. It discusses the Merkle-Damgard and sponge constructions commonly used to design hash functions. The document also summarizes the hash functions evaluated and selected in the NESSIE and CRYPTREC projects, such as Whirlpool, SHA-256, and SHA-512 in NESSIE and MD5, RIPEMD-160, and SHA-1 in CRYPTREC.
AN INVERTED LIST BASED APPROACH TO GENERATE OPTIMISED PATH IN DSR IN MANETS â...Editor IJCATR
Â
In this paper, we design and formulate the inverted list based approach for providing safer path and effective
communication in DSR protocol.Some nodes in network can participate in network more frequenctly whereas some nodes are not
participating. Because of this there is the requirement of such an approach that will take an intelligent decision regarding the sharing of
bandwidth or the resource to a node or the node group. Dynamic source routing protocol (DSR) is an on-demand, source routing
protocol , whereby all the routing information is maintained (continually updated) at mobile nodes.
This document summarizes a research paper on handwritten script recognition using soft computing techniques. The paper aims to recognize Hindi, English, and Urdu scripts using a combined approach of discrete cosine transform (DCT) and discrete wavelet transform (DWT) for feature extraction, and a neural network classifier. A database containing 961 handwritten samples across the three scripts was created, with 320 samples per script varying in font size. The system achieved a recognition accuracy of 82.70% on the test dataset containing 480 samples. The paper provides background on challenges in multi-script recognition and discusses preprocessing, segmentation, feature extraction and representation steps prior to classification.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Computational Engineering Research(IJCER)ijceronline
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International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Literature review of Digital SignatureAsim Neupane
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The document discusses digital signatures and how they work. It explains that a digital signature is an electronic signature that authenticates the identity of the sender and ensures the message has not been altered. It is generated by encrypting a message digest of the document with the sender's private key. This allows the recipient to decrypt the signature with the public key and verify that the message matches the original. The document then discusses how digital signatures can be made more efficient through the use of message digests, which provide a fingerprint of the data through a hash function. This allows signing just the digest rather than the entire message.
Image compression using negative formateSAT Journals
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Abstract This project deals with the compression of digital images using the concept of conversion of original image to negative format. The colored image can be of larger size whereas the image can be converted into a negative form and compressed, by applying a compression algorithm on it. Image compression can improve the performance of digital systems by reducing the time and cost for the storage of images and their transmission, without significant reduction in quality and also to find a tool for compress a folder and selective image compression. Keywords: Image Processing, Pixels, Image Negatives, Colors, Color Models.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Hiding Malicious Content in PDF Documentsdeathwing
Â
Proof-of-concept demonstration for a specific digital signatures vulnerability that shows the ineffectiveness of the WYSIWYS (What You See Is What You Sign) concept.
A Novel Steganography Technique that Embeds Security along with CompressionCSCJournals
Â
Problem faced by todayâs communicators is not only security but also the speed of communication. This paper provides a mechanism that increases the speed of communication by reducing the size of content; for this data compression method is used and security factor is added by using Steganography. Firstly, the focus has been made on Data Compression and Steganography. Finally, proposed technique has been discussed. In Proposed technique first data is compressed to reduce the size of the data and increase the data transfer rate. Thereafter on compressed data state table operation is applied to improve the security. Then, this is used as the input to the LSB technique of Steganography. At receiver end, firstly the LSB extraction technique is used, thereafter the state table operation in reverse form is applied and finally the original data is obtained. Hence our proposed technique is effective that can reduce data size, increase data transfer rate and provide the security during communication.
Text independent speaker identification system using average pitch and forman...ijitjournal
Â
The aim of this paper is to design a closed-set text-independent Speaker Identification system using average
pitch and speech features from formant analysis. The speech features represented by the speech signal are
potentially characterized by formant analysis (Power Spectral Density). In this paper we have designed two
methods: one for average pitch estimation based on Autocorrelation and other for formant analysis. The
average pitches of speech signals are calculated and employed with formant analysis. From the performance
comparison of the proposed method with some of the existing methods, it is evident that the designed
speaker identification system with the proposed method is superior to others.
TEXT STEGANOGRAPHIC APPROACHES: A COMPARISONIJNSA Journal
Â
This paper presents three novel approaches of text steganography. The first approach uses the theme of
missing letter puzzle where each character of message is hidden by missing one or more letters in a word
of cover. The average Jaro score was found to be 0.95 indicating closer similarity between cover and
stego file. The second approach hides a message in a wordlist where ASCII value of embedded character
determines length and starting letter of a word. The third approach conceals a message, without
degrading cover, by using start and end letter of words of the cover. For enhancing the security of secret
message, the message is scrambled using one-time pad scheme before being concealed and cipher text is
then concealed in cover. We also present an empirical comparison of the proposed approaches with some
of the popular text steganographic approaches and show that our approaches outperform the existing
approaches.
Improving the data recovery for short length LT codes IJECEIAES
Â
Luby Transform (LT) code is considered as an efficient erasure fountain code. The construction of the coded symbols is based on the formation of the degree distribution which played a significant role in ensuring a smooth decoding process. In this paper, we propose a new encoding scheme for LT code generation. This encoding presents a deterministic degree generation (DDG) with time hoping pattern which found to be suitable for the case of short data length where the well-known Robust Soliton Distribution (RSD) witnessed a severe performance degradation. It is shown via computer simulations that the proposed (DDG) has the lowest records for unrecovered data packets when compared to that using random degree distribution like RSD and non-uniform data selection (NUDS). The success interpreted in decreasing the overhead required for data recovery to the order of 25% for a data length of 32 packets.
Speech to text conversion for visually impaired person using Âĩ law compandingiosrjce
Â
The paper represents the overall design and implementation of DSP based speech recognition and
text conversion system. Speech is usually taken as a preferred mode of operation for human being, This paper
represent voice oriented command for converting into text. We intended to compute the entire speech processing
in real time. This involves simultaneously accepting the input from the user and using software filters to analyse
the data. The comparison was then to be established by using correlation and Âĩ law companding techniques. In
this paper, voice recognition is carried out using MATLAB. The voice command is a person independent. The
voice command is stored in the data base with the help of the function keys. The real time input speech received
is then processed in the speech recognition system where the required feature of the speech words are extracted,
filtered out and matched with the existing sample stored in the database. Then the required MATLAB processes
are done to convert the received data and into text form.
ADVANCED LSB TECHNIQUE FOR AUDIO STENOGRAPHYcsandit
Â
This work contributes to the multimedia security fields by given that more protected
steganography technique which ensures message confidentiality and integrity. An Advanced
Least Significant Bit (ALSB) technique is presented in order to meet audio steganography
requirements, which are imperceptibility, capacity, and robustness. An extensive evaluation
study was conducted measuring the performance of proposed NLSB algorithm. A set of factors
were measured and used during evaluation, this includes; Peak Signal to Noise Ratio (PSNR)
and Bit Error Rate. MP3 Audio files from five different audio generators were used during
evaluation. Results indicated that ALSB outperforms standard Least Significant Bit (SLSB)
technique. Moreover, ALSB can be embedding an utmost of 750 kb into MP3 file size less than 2
MB with 30db average achieving enhanced capacity capability.
The document describes the Huffman data compression algorithm. It was created in the 1950s by David Huffman to efficiently compress messages by assigning binary codes to characters based on their frequency, with more frequent characters getting shorter codes. This allows any message to be compressed in a lossless manner. The algorithm builds a binary tree from the character frequencies and reads codes from the tree to assign each character a unique code for compression.
Traid-bit embedding process on Arabic text steganography methodjournalBEEI
Â
The enormous development in the utilization of the Internet has driven by a continuous improvement in the region of security. The enhancement of the security embedded techniques is applied to save the intellectual property. There are numerous types of security mechanisms. Steganography is the art and science of concealing secret information inside a cover media such as image, audio, video and text, without drawing any suspicion to the eavesdropper. The text is ideal for steganography due to its ubiquity. There are many steganography embedded techniques used Arabic language to embed the hidden message in the cover text. Kashida, Shifting Point and Sharp-edges are the three Arabic steganography embedded techniques with high capacity. However, these three techniques have lack of performance to embed the hidden message into the cover text. This paper present about traid-bit method by integrating these three Arabic text steganography embedded techniques. It is an effective way to evaluate many embedded techniques at the same time, and introduced one solution for various cases.
The document proposes two techniques for hiding messages in digital images using steganography. The first technique encodes a secret message using punctuation marks before embedding it in an image. The second uses a modified scytale cipher to arrange the message bits in a grid that is then linearly embedded. Both techniques add an extra layer of protection on top of embedding in the image. Examples are provided demonstrating applying each technique using S-Tools software and analyzing the original versus stego-images.
This document summarizes an algorithm for hiding text within wave audio files. It begins by providing background on steganography and different techniques for embedding information, including within images, video, and audio files. It then describes the structure of digital audio files and how the least significant bit (LSB) manipulation technique works. The proposed algorithm embeds secret binary text into wave files by adding or subtracting a value from quantized phase coefficients of voiced audio blocks, depending on whether the secret bit is a 0 or 1. During extraction, the secret bits are reconstructed by determining whether the phase coefficient is greater than or less than the original quantized value. The algorithm is implemented in two phases - an embedding phase that hides the secret data in
We propose a model for carrying out deep learning based multimodal sentiment analysis. The MOUD dataset is taken for experimentation purposes. We developed two parallel text based and audio basedmodels and further, fused these heterogeneous feature maps taken from intermediate layers to complete thearchitecture. Performance measuresâAccuracy, precision, recall and F1-scoreâare observed to outperformthe existing models.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
HIDING A MESSAGE IN MP3 USING LSB WITH 1, 2, 3 AND 4 BITSIJCNCJournal
Â
This document summarizes a research paper that proposes a new steganography method for hiding text messages in MP3 audio files. The method randomly selects positions in the MP3 file to embed bits of the text message using the least significant bit (LSB) technique. The text message is embedded starting and ending with a unique signature or key. The methodology focuses on embedding one, two, three or four bits from the secret message into the MP3 file using LSB. The performance is evaluated based on robustness, imperceptibility and hiding capacity. Experimental results show the new method provides increased security compared to other LSB steganography methods.
IRJET - Hash Functions and its Security for SnagsIRJET Journal
Â
This document provides an overview of cryptographic hash functions, including their structure, properties, and selections in previous research projects. It discusses the Merkle-Damgard and sponge constructions commonly used to design hash functions. The document also summarizes the hash functions evaluated and selected in the NESSIE and CRYPTREC projects, such as Whirlpool, SHA-256, and SHA-512 in NESSIE and MD5, RIPEMD-160, and SHA-1 in CRYPTREC.
AN INVERTED LIST BASED APPROACH TO GENERATE OPTIMISED PATH IN DSR IN MANETS â...Editor IJCATR
Â
In this paper, we design and formulate the inverted list based approach for providing safer path and effective
communication in DSR protocol.Some nodes in network can participate in network more frequenctly whereas some nodes are not
participating. Because of this there is the requirement of such an approach that will take an intelligent decision regarding the sharing of
bandwidth or the resource to a node or the node group. Dynamic source routing protocol (DSR) is an on-demand, source routing
protocol , whereby all the routing information is maintained (continually updated) at mobile nodes.
This document summarizes a research paper on handwritten script recognition using soft computing techniques. The paper aims to recognize Hindi, English, and Urdu scripts using a combined approach of discrete cosine transform (DCT) and discrete wavelet transform (DWT) for feature extraction, and a neural network classifier. A database containing 961 handwritten samples across the three scripts was created, with 320 samples per script varying in font size. The system achieved a recognition accuracy of 82.70% on the test dataset containing 480 samples. The paper provides background on challenges in multi-script recognition and discusses preprocessing, segmentation, feature extraction and representation steps prior to classification.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Computational Engineering Research(IJCER)ijceronline
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International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Literature review of Digital SignatureAsim Neupane
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The document discusses digital signatures and how they work. It explains that a digital signature is an electronic signature that authenticates the identity of the sender and ensures the message has not been altered. It is generated by encrypting a message digest of the document with the sender's private key. This allows the recipient to decrypt the signature with the public key and verify that the message matches the original. The document then discusses how digital signatures can be made more efficient through the use of message digests, which provide a fingerprint of the data through a hash function. This allows signing just the digest rather than the entire message.
Image compression using negative formateSAT Journals
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Abstract This project deals with the compression of digital images using the concept of conversion of original image to negative format. The colored image can be of larger size whereas the image can be converted into a negative form and compressed, by applying a compression algorithm on it. Image compression can improve the performance of digital systems by reducing the time and cost for the storage of images and their transmission, without significant reduction in quality and also to find a tool for compress a folder and selective image compression. Keywords: Image Processing, Pixels, Image Negatives, Colors, Color Models.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This document provides an overview of lossless data compression techniques. It discusses Huffman coding, Shannon-Fano coding, and Run Length Encoding as common lossless compression algorithms. Huffman coding assigns variable length binary codes to symbols based on their frequency, with more common symbols getting shorter codes. Shannon-Fano coding similarly generates a binary tree to assign codes but aims for a roughly equal probability between left and right subtrees. Run Length Encoding replaces repeated sequences with the length of the run and the symbol. The document contrasts lossless techniques that preserve all data with lossy techniques used for media that can tolerate some loss of information.
The Internet is the essential wellspring of data in the present life where it offers the trade of data to the
clients.The exchange of such data prompts an incredible security danger. Cryptography and steganography
are two issues in security systems.Cryptography jumbles the message to be incomprehensible While
Steganography shroud the message To be invisible. Therefore, Encryption any private data before
concealing in the cover object will provide twofold security. This paper presents a technique for disguise
message with four levels of security where the message first encrypt using modifying vernam cipher, in
which the initial key originate automatically from random pixel of camouflage cover and alter continuously
along message length then embedded cipher message in grayscale cover image, after that encrypt this
cover using modifying vernam cipher also then embedded it in RGB color cover image. The simulation
consequence illustrates that the scheme provides better protection.
This document provides an overview of data communications and computer networks. It discusses key topics such as the difference between data communications and telecommunications, trends toward pervasive networking and integration of different communication types. It also covers implications for network management, such as how networks change business operations and the need for standards. The document then discusses different layers of the OSI model and their responsibilities. It provides examples of network standards bodies and implications for managing projects with different uncertainty levels. Finally, it summarizes several chapters that cover physical layer transmission methods, data link layer protocols, local area networks, and the network and transport layers of the OSI model.
Ijri ece-01-01 joint data hiding and compression based on saliency and smvqIjripublishers Ijri
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Global interconnect planning becomes a challenge as semiconductor technology continuously scales. Because of the increasing wire resistance and higher capacitive coupling in smaller features, the delay of global interconnects becomes large compared with the delay of a logic gate, introducing a huge performance gap that needs to be resolved A novel equalized global link architecture and driverâ receiver co design flow are proposed for high-speed and low-energy on-chip communication by utilizing a continuous-time linear equalizer (CTLE). The proposed global link is analyzed using a linear system method, and the formula of CTLE eye opening is derived to provide high-level design guidelines and insights.
Compared with the separate driverâreceiver design flow, over 50% energy reduction is observed.
This document summarizes a research paper that proposes a new technique for data embedding and extraction in high resolution AVI videos. The technique encrypts a secret message before embedding it by alternately changing the LSB and LSB+3 bits of alternate bytes in the cover video file. An index is also created for the secret information and placed in a video frame to aid extraction. This technique aims to provide higher security, capacity and robustness compared to typical data embedding methods. The paper discusses related work on digital steganography techniques and the proposed video steganography algorithm in more detail.
Communication TechnologiesCIS 505Business Informat.docxmccormicknadine86
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Communication
Technologies
CIS 505
Business Information
*
Welcome to Communication Technologies. In this lesson, we will discuss Business Information.
Next slide.
Topics
AudioDataImageVideoPerformance measures
*
The following topics will be covered in this lesson:
Audio;
Data;
Image;
Video; and
Performance measures.
Next slide.
AudioOverviewMeasured in bandwidthCan be represented digitallyApplicationsHuman voiceTelephoneTelemarketingVoice mailAudio teleconferencingEntertainment radioNetworking ImplicationsPBXCentrex
*
The audio service supports applications based on sounds, usually of human voice. The primary application using audio service is telephone communication. Other applications include telemarketing, voice mail, audio teleconferencing, and entertainment radio. The quality of sound is characterized mainly by bandwidth. Audio information can also be represented digitally.
The most effective way of managing voice requirements is to tie all of the phones at a given site into a single system. There are two main alternatives for this:
The private branch exchange, and
Centrex.
The private bank exchange, or PBX, is an on-premise switching facility, owned or leased by an organization that interconnects the telephones within the facility and provides access to the public telephone system.
Centrex is a telephone company offering that provides the same sort of service as a PBX but performs the switching function in equipment located in the telephone companyâs central office.
Either a PBX or Centrex facility can support a wide variety of voice-related services. Both voice mail and audio teleconferencing can be supported by either approach.
Next slide.
OverviewExamining Forms of Business InformationHow impact is measuredForms of business informationTypes of servicesInformation SourcesDigitalNumericalTextBinaryAnalog
*
It is important to understand how information communication relates to business requirements. A first step in this understanding is to examine the various forms of business information. Our examination covers the following topics:
How the impact of information sources on communications systems is measured,
The nature of the four major forms of business information,
The types of business services that relate to each of these forms of information, and
An introductory look at the implications of these services from the point of view of the communications requirements that they generate.
Information sources can produce information in digital or analog form. Digital information is presented as a sequence of discrete symbols from a finite alphabet. Examples are text, numerical data, and binary data.
Analog information is a continuous signal that can take on a continuum of values. An example is the electrical signal coming out of a microphone when someone speaks into it.
Next slide.
DataOverviewFinite alphabet of symbolsTextNumerical informationCharacter stringsBinary dataUsing a databaseNetwor ...
Ensure Security and Scalable Performance in Multiple Relay NetworksEditor IJCATR
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The document presents a novel technique for document image binarization that accurately segments foreground text from poorly degraded document images. The technique uses adaptive image contrast, which is a combination of local image contrast and local image gradient. This overcomes variations in text and background caused by degradation. It first constructs an adaptive contrast map, then binarizes and combines it with edge detection to identify text stroke edges. Local thresholding further segments text based on edge pixel intensities within a window. The method is simple, robust and requires minimal parameter tuning. It was shown to perform well on sample degraded document images.
A Novel Document Image Binarization For Optical Character RecognitionEditor IJCATR
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This paper presents a technique for document image binarization that segments the foreground text accurately from poorly
degraded document images. The proposed technique is based on the Segmentation of text from poorly degraded document images and
it is a very demanding job due to the high variation between the background and the foreground of the document. This paper proposes
a novel document image binarization technique that segments the texts by using adaptive image contrast. It is a combination of the
local image contrast and the local image gradient that is efficient to overcome variations in text and background caused by different
types degradation effects. In the proposed technique, first an adaptive contrast map is constructed for a degraded input document
image. The contrast map is then binarized by global thresholding and pooled with Cannyâs edge map detection to identify the text
stroke edge pixels. By applying Segmentation the text is further segmented by a local thresholding method that. The proposed method
is simple, strong, and requires minimum parameter tuning.
A Novel Document Image Binarization For Optical Character RecognitionEditor IJCATR
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This paper presents a technique for document image binarization that segments the foreground text accurately from poorly
degraded document images. The proposed technique is based on the
Segmentation of text from poorly degraded document images and
it is a very demanding job due to the high variation between the background and the foreground of the document. This paper pr
oposes
a novel document image binarization technique that segments t
he texts by using adaptive image contrast. It is a combination of the
local image contrast and the local image gradient that is efficient to overcome variations in text and background caused by d
ifferent
types degradation effects. In the proposed technique
, first an adaptive contrast map is constructed for a degraded input document
image. The contrast map is then binarized by global thresholding and pooled with Cannyâs edge map detection to identify the t
ext
stroke edge pixels. By applying Segmentation the
text is further segmented by a local thresholding method that. The proposed method
is simple, strong, and requires minimum parameter tuning
Notes for Advanced Image Processing subject. This subject comes under Computer Science for B.E./B.Tech and M.E./M.Tech. students. Hope this will help you.
AVC based Compression of Compound Images Using Block Classification SchemeDR.P.S.JAGADEESH KUMAR
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The document discusses a proposed method for compressing compound images using block classification and different compression schemes for different block types. The method classifies blocks of a compound image as background, text, hybrid, or picture blocks using a histogram-based approach. Different compression algorithms are then applied to different block types, including run-length encoding for background blocks, wavelet coding for text blocks, H.264 AVC with CABAC entropy coding for hybrid blocks, and JPEG coding for picture blocks. Experimental results showed that this block classification and compression scheme approach improved the compression ratio for compound images over single compression methods but increased computational complexity.
An Energy Efficient Data Secrecy Scheme For Wireless Body Sensor NetworksCSEIJJournal
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Data secrecy is one of the key concerns for wireless body sensor networks (WBSNs). Usually, a data
secrecy scheme should accomplish two tasks: key establishment and encryption. WBSNs generally face
more serious limitations than general wireless networks in terms of energy supply. To address this, in this
paper, we propose an energy efficient data secrecy scheme for WBSNs. On one hand, the proposed key
establishment protocol integrates node IDs, seed value and nonce seamlessly for security, then
establishes a session key between two nodes based on one-way hash algorithm SHA-1. On the other hand,
a low-complexity threshold selective encryption technology is proposed. Also, we design a security
selection patter exchange method with low-complexity for the threshold selection encryption. Then, we
evaluate the energy consumption of the proposed scheme. Our scheme shows the great advantage over
the other existing schemes in terms of low energy consumption.
Near Duplicate Document Detection: Mathematical Modeling and AlgorithmsLiwei Renäģģåå
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Near-duplicate document detection is a well-known problem in the area of information retrieval. It is an important problem to be solved for many applications in IT industry. It has been studied with profound research literatures. This article provides a novel solution to this classic problem. We present the problem with abstract models along with additional concepts such as text models, document fingerprints and document similarity. With these concepts, the problem can be transformed into keyword like search problem with results ranked by document similarity. There are two major techniques. The first technique is to extract robust and unique fingerprints from a document. The second one is to calculate document similarity effectively. Algorithms for both fingerprint extraction and document similarity calculation are introduced as a complete solution.
New Structure of Channel Coding: Serial Concatenation of Polar Codesijwmn
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This document summarizes a research paper that proposes a new channel coding structure using serial concatenation of polar codes. The proposed method concatenates two polar codes in series with an interleaver in between to rearrange bits. This is done to improve the reliability and performance of polar codes at low error rates. Experimental results show that the proposed serial concatenation of polar codes achieves a lower bit error rate than standard polar codes alone for different block lengths and code rates.
New Structure of Channel Coding: Serial Concatenation of Polar Codesijwmn
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In this paper, we introduce a new coding and decoding structure for enhancing the reliability and performance of polar codes, specifically at low error rates. We achieve this by concatenating two polar codes in series to create robust error-correcting codes. The primary objective here is to optimize the behavior of individual elementary codes within polar codes. In this structure, we incorporate interleaving, a technique that rearranges bits to maximize the separation between originally neighboring symbols. This rearrangement is instrumental in converting error clusters into distributed errors across the entire sequence. To evaluate their performance, we proposed to model a communication system with seven components: an information source, a channel encoder, a modulator, a channel, a demodulator, a channel decoder, and a destination. This work focuses on evaluating the bit error rate (BER) of codes for different block lengths and code rates. Next, we compare the bit error rate (BER) performance between our proposed method and polar codes.
New Structure of Channel Coding: Serial Concatenation of Polar Codesijwmn
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In this paper, we introduce a new coding and decoding structure for enhancing the reliability and performance of polar codes, specifically at low error rates. We achieve this by concatenating two polar codes in series to create robust error-correcting codes. The primary objective here is to optimize the behavior of individual elementary codes within polar codes. In this structure, we incorporate interleaving, a technique that rearranges bits to maximize the separation between originally neighboring symbols. This rearrangement is instrumental in converting error clusters into distributed errors across the entire sequence. To evaluate their performance, we proposed to model a communication system with seven components: an information source, a channel encoder, a modulator, a channel, a demodulator, a channel decoder, and a destination. This work focuses on evaluating the bit error rate (BER) of codes for different block lengths and code rates. Next, we compare the bit error rate (BER) performance between our proposed method and polar codes.
This document is a table of contents and introduction for a book titled "jQuery Fundamentals" by Rebecca Murphey. The book covers jQuery basics, core concepts, events, effects, Ajax, plugins, and advanced topics. It includes over 50 code examples to demonstrate jQuery syntax and techniques. The book is available under a Creative Commons license and the source code is hosted on GitHub.
This document provides a preface and table of contents for a book on jQuery concepts. The preface explains that the book is intended to teach intermediate and advanced jQuery concepts through code examples. It highlights some stylistic approaches used in the book, such as emphasizing code over text explanations and using color coding. It also defines some key terms that will be used, and recommends reviewing the jQuery documentation and understanding how the text() method works before reading the book. The table of contents then outlines the book's 12 chapters and their respective sections, which cover topics like selecting, traversing, manipulating, events, plugins and more.
This document discusses the field of computer forensics. It defines computer forensics as the collection, preservation, and analysis of computer-related evidence. The goal is to provide solid legal evidence that can be admitted in court and understood by laypeople. Computer forensics is used to investigate various incidents including human behavior like fraud, physical events like hardware failures, and organizational issues like staff changes. It aims to determine the root cause of system disruptions and failures.
This document discusses techniques for data hiding, which involves embedding additional data into digital media files like images, audio, or text. It describes several constraints on data hiding, such as the amount of data to hide, ensuring the data remains intact if the file is modified, and preventing unauthorized access to the hidden data. The document outlines traditional and novel data hiding techniques and evaluates them for applications like copyright protection, tamper-proofing, and adding supplemental data to files. It also discusses tradeoffs between hiding more data versus making the data more robust against modifications to the file.
This document summarizes an analysis of over 200,000 websites engaged in badware behavior according to Google's Safe Browsing initiative. The analysis found that over half of infected sites were located in China, with the top three Chinese network blocks accounting for 68% of infections in that country. In contrast, infected sites in the US were more distributed. Compared to the previous year, the total number of infected sites increased, likely due to expanded scanning and increased malware distribution through websites.
Steganography has been used for over 2500 years to hide secret messages. The paper explores steganography's history from ancient times through modern digital applications. It discusses early examples like Johannes Trithemius' steganographic treatise in the 15th century. Modern uses include microdots, digital images, audio, and digital watermarks for copyright protection. Terrorist groups may use steganography but there is no public evidence yet. Steganography continues to evolve with technology while attackers work to defeat new techniques.
The document discusses various cryptographic techniques including symmetric and asymmetric encryption. Symmetric encryption uses the same key for encryption and decryption, while asymmetric encryption uses two different keys. The document then describes the Data Encryption Standard (DES) algorithm and its variants, including Triple DES. It also covers the Advanced Encryption Standard (AES) algorithm, its design principles, and modes of operation for block ciphers like ECB, CBC, CFB and OFB.
This document discusses the topic of steganography, which is hiding secret messages within other harmless messages. It outlines different techniques for hiding messages in text, images, and audio files. For text, it describes line shift coding, word shift coding, and feature coding methods. For images, it explains least significant bit insertion and exploiting the limitations of the human visual system. For audio, it mentions low-bit encoding and other techniques like phase coding and spread spectrum. It also discusses steganalysis, which aims to detect and destroy hidden messages within files.
This document discusses the need for computer security and provides an introduction to key concepts. It explains that security is necessary to protect vital information, provide authentication and access control, and ensure availability of resources. The document then outlines common security threats like firewall exploits, software bugs, and denial of service attacks. It also discusses basic security components of confidentiality, integrity, and availability as well as goals of preventing attacks, detecting violations, and enabling recovery.
The document discusses various types of malicious programs including buffer overflows, viruses, worms, Trojan horses, backdoors, and logic bombs. It describes how buffer overflows can corrupt the program stack and be exploited by attackers. It explains that viruses attach themselves to other programs and replicate, worms replicate across networks, and Trojan horses masquerade as legitimate programs. It also outlines different approaches for antivirus software including signature-based, heuristic, activity monitoring, and full-featured protection.
This document discusses various topics relating to web security, including:
1) Different types of web pages like static, dynamic, and active pages and the technologies used to create them like JavaScript, Java, and CGI.
2) Security issues associated with technologies like ActiveX, Java applets, JavaScript, and cookies.
3) Protocols for secure communication like HTTPS, digital certificates, and single sign-on systems.
4) Methods for secure electronic commerce including SET and digital cash technologies.
This document provides an overview of network security topics including attacks like diffing, sniffing, session hijacking and spoofing. It discusses protocols for secure communication including SSL, TLS and IPSec. SSL and TLS provide security at the transport layer by encrypting data between a client and server. IPSec provides security at the network layer for both transport and tunnel modes. Authentication Header and Encapsulating Security Payload are the two security protocols used in IPSec.
This document provides an overview of network security topics including diffing, sniffing, session hijacking, spoofing, SSL, TLS, IPSec, and VPNs. It discusses how these attacks work and methods to protect against them, such as encryption. Network layer security protocols like IPSec are described, which uses authentication headers or encapsulating security payloads to provide security services to packets. Transport layer security protocols SSL and TLS are also summarized, including how they establish encrypted sessions between clients and servers.
This document discusses various topics related to computer security authorization, including multilevel security models like Bell-LaPadula and Biba's model, covert channels, inference control, CAPTCHAs, firewalls, and intrusion detection systems. It also provides an overview of network layers like the network layer, transport layer, TCP, and UDP. The key models discussed are Bell-LaPadula for confidentiality and Biba's model for integrity. Covert channels, inference control, and intrusion detection systems are described as techniques for authorization and access control.
This document discusses various methods of authentication, including message authentication, entity authentication, and digital signatures. It describes techniques such as hashing, message authentication codes (MACs), digital signatures using RSA, and challenge-response authentication. It also covers other authentication methods such as passwords, biometrics, and zero-knowledge proofs. The goal of authentication is to verify the identity of entities and ensure the integrity and authenticity of messages.
This document discusses the discrete-time Fourier transform (DTFT). It begins by introducing the DTFT and how it can be used to represent aperiodic signals as the sum of complex exponentials. Several properties of the DTFT are then discussed, including linearity, time/frequency shifting, periodicity, and conjugate symmetry. Examples are provided to illustrate how to compute the DTFT of simple signals. The document also discusses how the DTFT can be used to represent periodic signals and impulse trains.
This document discusses the continuous-time Fourier transform. It begins by developing the Fourier transform representation of aperiodic signals as the limit of Fourier series coefficients as the period increases. It then defines the Fourier transform pairs and discusses properties like convergence. Several examples of calculating the Fourier transform of common signals like exponentials, pulses and periodic signals are provided. Key concepts like the sinc function are also introduced.
Chapter3 - Fourier Series Representation of Periodic SignalsAttaporn Ninsuwan
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This document discusses Fourier series representation of periodic signals. It introduces continuous-time periodic signals and their representation as a linear combination of harmonically related complex exponentials. The coefficients in the Fourier series representation can be determined by multiplying both sides of the representation by complex exponentials and integrating over one period. The key steps are: 1) multiplying both sides by e-jĪ0t, 2) integrating both sides from 0 to T=2Ī/Ī0, and 3) using the fact that the integral equals T when k=n and 0 otherwise to obtain an expression for the coefficients an. Examples are provided to illustrate these concepts.
This document discusses linear time-invariant (LTI) systems in discrete time. It introduces the convolution sum representation of LTI systems, where the output of an LTI system with impulse response h[n] and input x[n] is given by y[n]=x[n]*h[n]=âk x[k]h[n-k]. Several examples are worked through to demonstrate calculating the output of an LTI system given its impulse response and input. The document also discusses representing discrete time signals as the sum of shifted unit impulse functions and properties of LTI systems like time-invariance.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
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Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
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Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
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Letâs explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
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This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
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Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
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"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analyticsâ feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
Main Java[All of the Base Concepts}.docxadhitya5119
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This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
How to Fix the Import Error in the Odoo 17Celine George
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An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
1. Electronic Marking and Identification Techniques
to Discourage Document Copying
J. Brussil, S. Low, N.Muxemchuk, L. O'Gormun
AT&T Bell Laboratories
Mumy Hill, NJ
Modern computer networks make it possible to
distribute documents quickly and economically by
elem"(* means rather tham by conventional paper
means. However. the widespread adoption of electronic
distribution of copyrighted muterial is currently impeded
by the euse of illirit copying und dissemination, In this
puper W O propose techniqut>s hut discourage illicii
distribution hv embedding each document with U unique
codeword. Our encoding techniques are indiscernible by
rruders. yei enable us to identifi th8e sanctioned
recipient of U document by emminution qf a recovered
docurneni. We propose three coding methods, describe
one in drtail, und present experimental results showing
that our identifieution techniques are highly reliable,
ellen ufter docwments have been photocopied.
1. Introduction
Electronic distribution of publications is increasingly
available through on-line text databases, CD-ROMs,
computer network based retrieval services, and
electronic libraries [Lesk90, Lynch90, Basch91,
Arms92, Saltzer92, Fox931. One electronic library, the
RightPages' Service [Hoffman93. Stoiy92.
O'Gorinan92I. has been in place within Bell
Laboratories since 1991, and lhas recently been installed
at the University of Califomia in San Francisco.
Electronic publishing is being driven by the decreasing
cost of computer processing and high quality printers
and displays. Furthermore, the increased availability of
low cost, high speed data communications makes it
possible to distribute electronic documents to large
groups quickly and inexpensively.
While photocopy infnngements of copyright have
always concerned publishers, the: need for document
security is much greater for electronic document
distribution (Garrett91, Vizard931. The s a " advances
that make elcctronic publishing and distribution of
documents feasible also increase the threat of
"bootlegged" copies. With far less effort than it takes to
copy a paper document and mail it to a single person, am
electronic document can be sent to a large group by
electronic mail. In addition, while originals and
photocopies of a paper document cLm look and feel
different,copies of electronic documents are identical.
In order for electronic publishing to become
accepted, publishers must be assured that revenues will
not be lost due to theft of copyrighted materials.
Widespread illicit document dissemination should
ideally be at least as costly or difficult ;is obtaining the
documents legitimately. Here we define "illicit
dissemination" as distribution of documents without ihe
knowledge of - arid payment to - the publisher; tltiis
contrasts legitimate document distribution by ihe
publisher or the publisher's electronic documtmt
distributor.This paper describes a ineatns of discouraging
illicit copying and dissemination. A document is marked
in an indiscernible way by a codeword identifying ihe
registered owner to whom the document is smt. If' ;I
document copy is found that is suspected to have been
illicitly disseminated, that copy can be decoded and ihe
registered owner identified.
The techniques we describe here are complementary
to the security practices that can be applied to ihe
legitimate distribution of documents. For example, ;I
document can be encrypted prior to transmission across
a cornputer network. Then even if the tlocuinent file is
intercepted or stolen from ;t database, it remains
cnreadable to those not possessing the decrypting kt:y.
The techniques we describe in this paper prcwiide
security ajier a document has been decrypted. and is thus
reatdible to all. We also briefly describe a cryptographic
protocol in Section 3 of this paper to secure ihe
document transmission process.
1. RightPages is a trademark of AT&T
1278
1Oa.2.1
0743-166W94 $3.000 1994 IEEE
2. In addition to discouraging illicit dissemination of
documents distributed by computer network, our
proposed encoding techniques can also make paper
copies of documents traceable. In particular, the
codeword embedded in each document survives plain
paper copying. Hence, our techniques can also be
applied to "closely held" documents, such as
confidential, limited distribution correspondence. We
describe this both as a potential application of the
methods and an illuslrationof their robustness in noise.
2. Document Coding Methods
Document marking can be achieved by altering the text
formatting, or by altering certain characteristics of
textual elements (e.g., characters). The goal in the
design of coding methods is to develop alterations that
are reliably decodeable (even in the presence of noise)
yet largely indiscernible to the reader. These criteria,
reliable decoding and minimum visible change, are
somewhat conflicting; herein lies the challenge in
designing document marking techniques.
The marking techniques we describe can be applied
to either an image representation of the document or to a
document format file. The document format file is a
computer file describing the document content and page
layout (or formatting), using standard format description
languages such as PostScript2,TeX, @off,etc. It is from
this format file that the image -what the reader sees -
is generated. The image representation describes each
page (or sub-page) of a document as an array of pixels.
The image may be bitmap (also called binary or black-
and-white), gray-scale, or color. For this work, we
describe both document format file and image coding
techniques, however we restrict the latter to bitmaps
encoded within the binary-valued text regions.
Common to each technique is that a codeword is
embedded in the document by altering particular textual
features. For instance, consider the codeword 1101
(binary). Reading this code right to left from the least
significant bit, the lirst document feature is altered for bit
1, the second feature is not altered for bit 0, and the next
two features are altered for the two 1 bits. It is the type
of feature that distinguishes each particular encoding
method. We describe these features for each method
below and give a simple comparison of the relative
advantages and disadvantages of each technique.
2. PostScriptis a trademark of Adobe Systems, Inc
The three coding techniques that we propose
illustrate different approaches rather than form <an
exhaustive list of document marking techniques. The
techniques can be used either separately orjointly. Each
technique enjoys certain advantages or applicability as
we discuss below.
2.1 Line-Shift Coding
This is a method of altering a document by vertically
shifting the locations of text lines to encode the
document uniquely. This encoding may be applied
either to the format file or to the bitmap of a page image.
The embedded codeword may be extracted from the
format file or bitmap. In certain cases this decoding can
be accomplished without need of the original image,
since the original is known to have uniform line spacing
between adjacent lines within a paragraph.
2.2 Word-ShiftCoding
This is a method of altering a document by horizontally
shifting the locations of words within text lines to
encode the document uniquely. This encoding CM be
applied to either the format file or to the bitmap of a
page image. Decoding may be performed from the
format file or bitmap. The d o d is applicable only to
documents with variable spacing between adjacent
words. Variable spacing in text documents is commonly
used to distribute white space when justifying text.
Because of this variable spacing, decoding requires the
original image - or more specifically, the spacing
between words in the unencoded document. See Figure
1 for an example of word-shift coding.
- f
Now is the time for all men/women to ...
Now is the time for all men/women to ...
Figure 1 -Example of word-shift coding. In a), the top
text line has added spacing before the "for,"the bottom
text line has the same spacing after the "for."In b), these
same text lines are shown again without the vertical lines
to demonstrate that either spacing appears natural.
Consider the following example of how a document
might be encoded with word-shifting. For each text line,
the largest and smallest spacings between words are
found. To code a line, the largest spacing is decremented
1Oa.2.2
1279
3. by some amount and the smallest is augmented by the
same amount. This maintains the text line length, and
produces little qualitative change to the text image.
2.3 Feature Coding
This is a coding method that is applied either to a format
file or to a bitmap image of iI document. The image is
examined for chosen text features, and those features are
altered, or not altered, depending on the codeword.
Decoding requires the oniginal image, or more
specifically, a specification of the change in pixels at a
feature.There are many possible choices of text features;
here, we choose to alter upward, vertical endlines-. that
is the tops of letters, b, d, Ii, etc. These endlines are
altered by extending or shortening their lengths by one
(or more) pixels, but otherwise not changing the endline
feature. See Figure 2 for an example of feature coding.
Figure 2 - Example shows feature coding performed
on a portion of text from a jourinal table of contents. In a),
no coding has been applied. In b), feature coding has
been applied to select characters. In c), the feature
coding has been exaggerated to show feature
alterations.
Among the proposed encoding techniques, line-
shifting is likely to be the niost easily discemible by
readers. However we also expect line-shifting to be the
most robust type of encoding in the presence of noise.
This is because the long lengrhs of text lines provide a
relatively easily detectable feature For this reason, line
shifting is particularly well suited to marking documents
to be distributed in paper form, where noise can be
introduced in printing and phottmpying. As we will
show in Section 4, our experiments indicate that we can
easily encode documents with line shifts that 'are
sufficiently small1 that they are not noticed by the casual
reader. while stillretaining the ability to decode reliably.
We expect that word-shifting will be less discernible
to the reader than line-shifting, since the spacing
between adjacent words on ,a line is often varied to
support text justification. Feature encoding can
accommodate a particularly large number of sanctioned
document recipients, since there are frequently two or
more features available for encoding in each word.
Feature alterations are also largely indiscernible to
readers. Feature encoding also has the additional
advantage that it can be applied directly to image files.
which allows encoding to be introduced in the absence
of a format file.
A technically sophisticated "attacker" C M detect that
a document has been encoded by any ot the three
techniques we have introduced. Such an attacker cain
also attempt to remove the encoding (e.g., produce ;U)
unencoded document copy). Our goal in the design oi
encoding techniques is to make successtul attacks
extremely difficult or costly. We will return to ;I
discussion of the difficulty ot dcfeating each of our
encoding techniques in Section 5.
3. Transmission Security by Cryptographic Protorol
A publisher CM distribute documents as either image or
format files. The coding methods described above are
intended to discourage illicit copying and dissemination
of read7ble images. However. before a docurnen1 IS to he
displayed or printed (e.g., dunng transmission on ai
computer network), the document can he secured by
king encrypted. Though this paper pnmarilv describes
image coding methods, we briefly describe ,I complcte
system for document security using ai cryptographic
protocol proposed to secure transmitted documrnn
against theft [Choudhury931.
The proposed cryptographictechniques for document
distribution use both public key and secret key
cryptography.Each document recipient has a public kcy,
P K, with which anyone can cncode information, antl ai
private key, SH, with which only thc reiiprent a n
decode the information. The publisher first sc lids the
recipient a program to process a document. The progriun
is changed often. to reduce the value of reveiw
engineering the program. The program includes a secret
key, SD,that is encrypted with P R , so Ihat only ihe
individual with S R can run the program antl recover SII.
The document that is transmitted by the publisher is
encrypted so that S D is required to receive it. 4lthough ;I
user may be willing to share the program and document.
it is assumed that S R is too valuable to pvi: away.
Perhaps it is the same key that is used in .I signature
system to charge purchases of docurnents. (It is unliki.ly
that anyone would give his credit card to a person who is
unscrupulous enough to violate the copyright la^ s.)
The information transmitted by the publisher
includes a unique identification number antl ii format
file. The same format file is transmitted to every
recipient, which rnakes things easier for the publisher by
keeping document preparation and secure tlistributi'on
separate. The program on the recipient's computer
1280
4. - requests S R from the recipient,
- uses S R to decrypt S D ,
- uses SD to decrypt the identification number and
- generates the image file with the identification
This example illustrates that the image encoding
techniques introduced in this paper may be viewed as
one component of a larger, secure document distribution
system.
format file, and
number encoded in the image.
4. Implementationand Experimental Results for Line-
Shift CodingMethod
In this section we describe in detail the methods for
coding and decoding we used for testing the line-shift
coding method. Each intended document recipient was
preassigned a unique codeword. Each codeword
specified a set of text lines to be moved in the document
specifically for that recipient. The length of each
codeword equaled the maximum number of lines that
were displaced in the area to be encoded. In our line-
shift encoder, each codeword element belonged to the
alphabet (- 1, +1, 01, corresponding to a line to be
shifted up, down or remain unmoved.
Though our encoder was capable of shifting an
arbitrary text line either up or down, we found that the
decoding performance was greatly improved by
constraining the set of lines moved. In the results
presented in this paper, we used a differential (or
difference) encoding technique. With this coding we
kept every other line of text in each paragraph unmoved,
starting with the first line of each paragraph. Each line
between two unmoved lines was always moved either up
or down. That is, for each paragraph, the lst, 3rd, 5th,
etc. lines were unmoved, while the 2nd, 4th, etc. lines
were moved. This encoding was partially motivated by
image defects we will discuss later in this section. Note
that the consequence of using differential encoding is
that the length of each codeword is cut approximately in
half. While this reduces the potential number of
recipients for an encoded document, the number can still
be extremely large. In each of our experiments we
displaced at least 19 lines, which corresponds to a
potential of at least 219 = 524,288 distinct
codewords/page. More than a single page per document
can be coded for a larger number of codeword
possibilitiesor redundancy for error-correction.
Each of our experiments began with a paper copy of
an encoded page. Decoding from the paper copy first
required scanning to obtain the digital image.
Subsequent image processing improved detectability;
salt-and-pepper noise was removed [OâGorman92] <and
the image was deskewed to obtain horizontal text
[OâGorman93]. Text lines were located using a
horizontal projection profile. This is a plot of the
summation of ON-valued pixels along each row. For a
document whose text lines span horizontally, this profile
has peaks whose widths are equal to the character height
and valleys whose widths are equal to the white space
between adjacent text lines. The distances between
profilepeaks are the interline spaces.
The line-shift decoder measured the distance
between each pair of adjacent text line profiles (within
the page profile). This was done by one of two
approaches -either we measured the distance between
the baselines of adjacent line profiles, or we measured
the difference between centroids of adjacent line
profiles. A baseline is the logical horizontal line on
which characters sit; a centroid is the center of mass of a
text line profile. As seen in Figure 3, each text line
produces a distinctive profile with two peaks,
corresponding to the midline and baseline. The peak in
the profile nearest the bottom of each text line is taken to
be the baseline. To define the centroid of a text line
precisely, suppose the text line profile runs from SCM
line y, y +1, ,to y +w, and the respective number of
ON bitdscan line are h(y), h ( y + l ) , a . . , h(y+w).
Then the text line centroid is given by
Y M Y ) + ... + (Y+w)h(Y+w) . (3.1)
The measured interline spacings (i.e., between adjacent
centroids or baselines) were used to determine if white
space has been added or subtracted because of a text line
shift. This process, repeated for every line, determined
the codeword of the document - this uniquely
determined the original recipient.
We now describe our decision rules for detection of
line shifting in a page with differential encoding.
Suppose text lines i - 1 and i +1 are not shifted and text
line i is either shifted up or down. In the unaltered
document, the distance between adjacent baselines, or
baseline spacings, are the same. Let si-l and sibe the
distances between baselines i - 1 and i, and between
baselines i and i + 1, respectively, in the altered
document. Then the baseline detection decision rule is:
h ( y ) + * * a + h ( y + w )
ifsi-l >si : decide line i shifted down
ifsi-1 <si : decide line i shifted up (3.2)
otherwise : uncertain
1Oa.2.4
1281
5. ON
bits
500
-0
I
-0
I
1000
I
2000
I
3000
scan Line
Figure 3- Profile of a recovered document page. Decoding a page with line shifting requires measuring the distances
between adjacent text line centroids; (marked with 0 ) or baselines (marked with +) and deciding whether white space has
been added or subtracted.
Unlike baseline spacings, centroid spacings between
adjacent text lines in the original unaltered documentare
not necessarily uniformly spaced. In centroid-based
detection, the decision is based on the difference of
centroid spacings in the altered and unaltered
documents. More specifically, let s,-~and s, be the
centroid spacings between lines i - 1 and i, and between
lines I and i +1, respectively,in the altered document; let
1 . and t , be the correspondingcentroid spacings in the
unaltered document. Then the centroid detection
&cision ride is:
s,-,-t,-, > s - t , decidelineishifieddown
decide line i shifted up(3.3)otherwise
An error is said to occur if our decoder decides that a
text line was moved up (down) when it was moved down
(up). In baseline detection, a second type of error exists.
We say that the decoder is uncertain if it cannot
determine whether a line wa.. moved up or down. Since,
for our encoding method, every other line ils moved and
this information is known to the decoder, false a l " m do
not occur.
4.1 Experimental Results for Line-Shift Coding
We conducted two sets of experiments. The firs1 set
tested how well line-shift coding works with different
font sizes and different line spacing shifts in the presence
of limited, but typical, image noise. The second set
tested how well a fixed lint: spacing shift could be
detected as document degradation became increasingly
severe. In this section, we ffirst describe these
experiments and then present our results.
The equipment we used in both experiments was as
follows: a Ricoh FSlS 400 dpi Flat Bed Electronic
Scanner, Apple Laserwriter IIntx 300 dpi laser printer,
and a Xerox 5052 plain paper copier3. The printer and
copier were selected in part because they are typical of
equipment found in wide use in office environments.
The particular machines we used could be characterizd
asbeing heavily used hut well maintamed.
Writing the software routine to implement a
rudimentary line-shift encoder for a PostScript input file
was simple. We chose the PostScript format because: 1)
it is the most common Page Description Language in use
ioday, 2) it enables us to have sufficiently fine control of
text placement, and 3) it permits us to encode documents
produced by a wide variety of word processing
applications. PostScript describes the document content
;I page at a time. Roughly speaking, it specifies ihe
content of a text line (or text line fragment such ;ISa
phrase, word, or character) and identifies the location lor
the text to be displayed. Text location is specified by (in
x-y coordinate representing a position on a virtual page.
'Though it depends on the application software
generating the PostScript, text placement can ~vpically
be modified by as little as U720 inch (approxiinately
1/10 of a printer's "point"). Most personal laser printcrs
in common use today have ahout half this resolution
(e.g., U300 inch).
'3. Xerox and 5052 are trademarks of Xerox Corp. Apple and
LaserWnter are trademarks of Apple Computer, Inc. Kicoh and
FSl are trademarks of Ricoh Cop
1282
1Oa.2.5
6. 4.1.1 Variable Font Size Experiment The first set of
experimentseach used a single-spacedpage of text in the
Times-Roman font. The page was coded using the
differential encoding scheme. We performed nine
experiments using font sizes of 8, 10, or 12 points and
shifting altemate lines (within each paragraph) up or
down by 1, 2, or 3 pixels. Each page of 8, 10, and 12
point size text extended for 23, 21, and 19 lines,
respectively. Different numbers of encoded lines per
page arise naturally, since as the font size dccreases,
more lines can be placed on the page, permitting more
information to be encoded. Since our printer has a 300
dpi resolution, each pixel corresponds to 1/300 inch, or
approximately one-quarter point. Each coded page was
printed on the laser printer, then copied three times. We
will refer to the laser printed page as the 0th copy: the
nth copy, n21, is produced by copying the n - 1st copy.
The third copy was then decoded to extract the
codeword. That is, we electronically scanned the third
copy, processedthe bitmap image to generatethe profile,
processed the profile to generate the text line spacings
(both baseline and centroid spacings), and detected the
codeword using these measurementsand rules (3.2-3).
The results of the variable font size experiment were
extremely good for all cases. Using the centroid
detection method, all line shifts were successfully
detected without error. Using the baseline detection
method, all line shifts for the 10 point font size were
successfully detected without error. All line shifts of 2
and 3 pixels were also detected without error for the 8
and 12 point size cases. For 8 point size text with 1
pixel spacing, 18 of 23 line shifts were correctly
detected, though the remaining 5 line shifts were deemed
uncertain. For 12 point size text with 1 pixel spacing,
18 of 19 line shifts were correctly detected, while 1 line
shift was incorrectly detected (i.e. 1 error). In summary,
both baseline and centroid approaches detected without
error for spacings of at least 2 pixels: the centroid
approach also had no errors for a 1pixel spacing.
Though it is not apparent from the results we have
stated, it is noteworthy that some variability will occur
in the detection performance results, even in repeated
"decoding"of the same recovered page. This variability
is due in part to randomness introduced in electronic
scanning. If a page is scanned several times, different
skew angles will ordinarily occur. The skew will be
corrected slightly differently in each case, causing
detection results to vary.
To illustrate this phenomena, we rescanned in the
test case (8 point text, 1 pixel spacing) 3 additional
times. The initial text line skew angle (i.e., before
deskewing) differed for each scan. In the three rescans,
we observed the following decoding results under
baseline detection: 5 uncertain, 3 uncertain and 1error,
and 6 uncertain. The line spacings that could not be
detected or were in error varied somewhat across the
retries. This suggests that there may be some decoding
performance gained by scanning a single page multiple
times, and combining the results (e.g., averaging).
4.1.2 Plain Paper Copying Experiment For the second
set of experiments, we encoded a single-spaced page of
text using differential encoding. We used a 10 point
Times-Roman font, and a 1 pixel line shift. Twenty-one
lines were shifted on the page. We then made repeated
copies (the lst, ..., 10th copy) of the page, and used each
copy in a separate experiment. Hence, each successive
experiment used a slightly more degraded version of the
same text page.
Detection results were surprisingly good. The
centroid detection method successfully detected all 21
line shifts for each generation of photocopy (through the
10th copy). The baseline detection method successfully
detected all lines on every copy generation, with the
following exceptions: 1error was made on the 4th, 5th,
6th, 7th and 10th copy, 2 errors on the 9th copy: 1
uncertain on the 3rd, 4th,'and 10th copy, 2 uncertains on
the 7th copy, and 4 uncertains on the 8th copy. In
summary, the baseline detection method successfully
detected at least 16 line shifts on each copy generation.
Though further testing must be done to understand
better how the coding is affected by noise, our results
indicate that, for baseline decoding, detection errors and
uncertainties do not increase monotonically with the
number of copies. Further, the line spacings that could
not be detected correctly varied somewhat from copy to
copy. This suggests that line spacing "information" is
still present in the text baselines, and can perhaps be
made available with some additional processing.
We have reported the uncoded error performance of
our marking scheme. But the 21 line shifts used in the
experiment were not chosen arbitrarily. The 21 line
shifts comprised 3 concatenated codewords selected
from a Hamming (7,4) block code, a 1-error correcting
code. Had we chosen to make use of this error
correction, roughly each third of apage would have been
protected from 1 error. Many, but not all, of the baseline
decoding errors and uncertainties would have been
corrected by this encoding. Of course, using an error-
correcting code would require increasing the number of
line shifts to produce the same maximum number of
uniquely encoded documents. We expect to use error
correction to increase detection performance in future
experiments,particularly those where text displacements
1283
1Oa.2.6
7. are smaller than those we have considered here. We also
expect that interleaving codewords across one or more
pages will improve overall detectionperformance.
Our experimental results reveal that centroid-based
detection outperformsbaseline-based detection for pages
encoded with sinall line shifts (i.e., 1 pixel) and subject
to large distortion. This performance difference arises
largely because baseline locations are integer-valued,
while centroid locations, being averages, are real-valued.
Since baseline locations are determined by detection of ;I
pe,& in the text line profile, this location can be of low
;iccuracy when the peak is not sharp due to some page
skew, noise, a short text line, etc. A single scan line error
in locating a text baseline is sufficient to introduce a
detection error when text lines are encoded with a 1
pixel shift.
Though the use of centroids is less subject to certain
imaging defects than are baselines, baseline coding
provides other benefits. In particular, encoded
documents c,m be decoded without reference to the
original, unaltered document. A secure document
distributor would then be relieved of the need to
maintain a library of original document centroid
spacings for decoding. Of course, both detection
techniques can be used jointly to provide d particularly
robust, low error probability detection scheme.
1.2 Discussion and Implications of Image Defects
Iniage defects [Baird92] resulting from plain paper
copying are all too familiar to the reader. We now briefly
discuss the defects most significantly affecting our
detection results. Our discussion is largely qualitative-
a inore quantitativediscussion of image defects and their
physical underpinnings is bt:yond the scope of this
paper.
The primary troublesomedefect we encountered was
text line skew, or the rottition of text lines about a point.
In most experiments we observed skew angles between
I-3", +lo]. Text line skew w;s largely removed by
iniage rotation, at the expenrie of the introduction ot
some distortion due to bilinear intt:rpolation of sampled
data.
Blumng also increased with the number of copies
produced. However, blurring seemed to have
surprisingly minor implications in detection
performance. It is possible that blurring introduces noise
in a symmetrical fashion on text lines, so it does not
contribute significantly to displacing centroid locations.
Plain paper copies were produced at the copier'y
nominal "copy darkness" setting; blurring typically
increases with copy darkness. As the number of copies
increased, copy darkness generally varied over a page;
regions of severe fading were sometimes observed. It is
unclear whether blurring or fading is inore detrimental to
decoding performance.
Expansion or shrinking of copy size IS another
potential problem. It is not unusual to discover a 4%
page length or width change after 10 copies. Further,
expansion dong the length and width of a page can he
markedly different. Copy size changes forced us to use
differential encoding -that is, encoding information in
the relative rather than absolute shifts between adjacent
text lines.
4.3 An Analytical Noise Model
In this subsection we present a siinple model of the noise
affecting text line centroids. We distinguish t n o types
of noise. The first type of noise models the distortion in
printmg and scanning the document; the second type
models the distortion in copying. This second type of
noise increases with the number of copies while the first
type does not.
An unaltered page of text with N +1 text lints yields
n +1 vertical coordinates y , ... .yn+ I , that represent
the centroids of the text lines. measured froin, say. the
top page margin. The centroid spacings, or distance in
scan lines between adjacent centroids, are given by
t , = Y!+l -- it, I = I , . . .n (4.1)
Hence, for detecting line-shifts, ;I page of N + I text lines
IS effectively describedby n centroid spacings
The ith line spacing shift c, IS positlve if extra space
has been added, negative if space has been suhtractrd.
and zero otherwise. This line spacing shift changes the
original ith centroid spacing from 1, to I , + c L Let 4
be the ith centroid spacing in the jth copy of ai) altered
document. The printer noise, v,, models the cumulative
effect (on the ith centroid spacing) of distortiton
introduced by printing, scanning, and iinage processing.
We assume that the printer noise v, is strictly &iitive
'and logically distorts the centroid spacings of the
original paper copy 10
sy = f i + ci + v i , i = 1, ' .. . t i , (4.2)
where v,, i = 1. ... ,n, are independent and identically
distributed Gaussian random variables. This assumption
is supported by our measurements, which yield a mean
of pI=0.0528 pixel and variance of o: =0.140 pixel'.
Let N{ be the random noise that surntnaim the
cuinulative effect of skewing, scaling. and otlier
photographic distortions introduced on the I th centroid
spacing 4-l by making the jth copy. Then the centroid
1Oa.2.7
1284
8. spacings on thejth copy are
4 = 4-i + N:, i = l ; . . , n , j = 1 ; . . , ~ . (4.3)
Hence, the centroid spacing $ is corrupted by the
cumulative noise:
$ = SP + (Nf+ + N j ) . (4.4)
Since the physical processes of printing, scanning, and
image processing are independent of copying, we will
assume that the random variables vi , i = 1, ... ,n, are
independent of N ; , i = l ; . . , n ; j = l ; . . , K . Our
measurements suggests a surprisingly simple statistical
behavior for the random copier noise. The noise
components N;,j = 1,2, . .- ,K, are well approximated
by i.i.d. Gaussian random variables with mean
p2=0.066 pixel and variance 0;=0.017 pixel'. Hence,
the centroid spacing $ on thejth copy is
$ = sp + qj, i = l , ... ,n, (4.5)
where q; is Gaussian with meanjp2and variancejo;.
We now combine printer noise and copier noise to
estimate the "bit" error probability under centroid
detection. Consider three adjacent, differentially
encoded text lines labeled such that lines i - 1 and i +1
are unshdted while line i is shifted (up or down) by 1c 1
pixels. The corresponding centroid spacings $-I and 4
on thejth copy are
.$-I. = ti-1 + c + v,-l + 171-1 (4.6)
(4.7).$ = ti - c + vi + qj,
where q; are defined as in (4.5).
Next define the decision variable
D (vi-l -vi)+(qjy1-qi). Since the random
variables v i - l , v i , q{-l,q{ are mutually independent,
the variable D is Gaussian with zero mean and variance
2(O: +io;>.
Now suppose the jth copy of the document is
recovered and is to be decoded. Applying (4.6-7) to the
centroid detection decision rule (3.3) and simplifying
yields
$0 > - 2c : decide line i shifted down
Hence, the probability that a given line shifted by 1 pixel
is decoded in error is
otherwise : decide line i shifted up. (4.8)
p(decide up sh$t I down shift) p(down shifr) +
p(decide down sh$t I up shift) p(up shift) (4.9)
= p ( D I - 2 ) p(down shift) + p ( D > 2 ) p(up shift)
= p ( D >2). (4.10)
The error probability is easily evaluated using the
complementary error function. Using the measurements
&=O. 140 pixel2 and 0;=0.017 pixel', the probability
that a 1 pixel line shift is decoded in error is only
approximately 2% on the 20th copy.
5. Detecting and Defeating Image Encoding
It appears that all document coding schemes, including
the ones introduced in this paper, can be detected and
defeated. Successful attacks on encoded documents
arguably involve substantial technical sophistication and
effort. The sophistication of successful attacks can vary,
introducing various tradeoffs. For example, document
presentation quality may be sacrificed by the process of
removing an encoding. An extreme case is for an
attacker simply to obliterate an encoding by adding
enough noise to render an image undecodeable,
however, this may also render the document illegible or
marginally legible.
Hence our objectives in designing attack-resistant
image coding schemes are ideally to
1. ensure that substantial effort is required to a
remove a document encoding, and
2. require that a successful attack will result in a
substantial loss of document presentation quality.
In short, the "cost" of theft should exceed the cost of
obtaining a document legitimately. In practice, however,
we can realize the above objectives only in part. But
establishing any barrier to illicit copying and
dissemination provides a greater level of document
security than publishers now enjoy.
We next describe some illustrative techniques to
defeat our document marking methods. We comment on
their efficacy and ease of implementation, though we
acknowledge that there is a lack of accepted measures to
gauge the degree of difficulty necessary for each attack.
We also discuss approaches to detect the presence of
document coding, though it is generally not necessary to
detect the presence of an encoding to defeat it.
5.1 Defeating the Line-Shift Coding Method
Though line shifts are difficult for the casual reader to
discern, they may be found relatively easily by manual
or automatic measurement of the number of pixels
between text baselines. An attacker can invoke a pixel
magnifying glass (a common computer graphics tool)
and manually count pixels between adjacent text lines on
a page. If adjacent text lines (within a paragraph) are
nonuniformly spaced, then the attacker can surmise that
encoding has been performed, and precisely measure the
displacement introduced by the encoding.
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9. Certain pattern recognition tools, such as the
horizontal projection profile, can be used to determine
text line spacing automatically. The projection profile is
;I summation of the âonâ pixels along each row in an
nmage; each text line has a corresponding peak in the
profile. Therefore, the spacing between adjacent peaks
ideally gives text line spacing. However, complications
can arise in measuring spacing automatically. For
instance, if a document is skewed (line orientations not
exactly on the horizontal), then the accuracy of spacings
measured by the projection profile will decrease. If a
document has multiple columns, each column must first
bc. extracted to measure itâs line syacing.
Line-shift coding can be eliminated by respacing
lines either uniformly or randomly. This requires either
manual or automatic cut-and-paste of lines. This process
is difficult to automate if the document contains figures
or multiple columns, or is skewed. Respacing lines
randomly runs the risk of further decreasing (increasing)
line spaces that are already short (long), possibly
enabling a casual reader to notice that the document has
been t pered.
If a document marked with line-shifting is
dismbuted in paper form, it is particularlychallenging to
remove the encoding. Of course an attacker can return
each page to the electronic domain by scanning, use the
above methods, then reprint the document. Removing
the encoding from a paper document which itself is a
photocopy is even more challenging. Image defects such
as component blurring, salt-and-pepper noise, and non-
linear tr:nslatlon within a page, all can potentially
combine to disrupt w automated attack.
5.2 Defeating the Word-Shift Coding Method
The prescnce of word spacing encoding can be detected
in either of two ways. One way is to know or ascertain
the spacing algorithm used by the formatter for text
justification. Actual spaces between words could then
be measured and compared to the formatterâs expected
spacing. Spacing differences resulting from this
comparison would reveal the location and size of text
displacements. The second way is to take two or more
distinctly encoded, uncorrupted documents and perfonn
a page by page pixel-wise difference operation on the
corresponding page images. Such a comparison would
quickly indicate the presence of word shifts, and the size
of the word displacement.
An attacker can eliminate the encoding by respacing
shifted words back to the original spacing produced
under the formatterâs rule. An alternative attack is
merely to apply random horizontal shifts to all words in
the docuinent not found at column edges. Word shifting
can be done manually using cut-and-paste graphics tools,
though producing a document without severe
presentation degradation would be time-consuming and
painstaking. To perform word-shifting automatically,
each text baseline must first be found (perhaps as
described in Section 5.1), then individual words
segmented, and their spacing ch,anged along the
baselines. Words CM be segmented by comparing intra-
word character spacing to inter-word spacing. However,
current segmentation methods are prone to errors
introduced by font changes, font size changes, symbols,
equations, etc. These complications would likely requnre
manual inspection and intervention for repair, again a
time-consumingand painstaking process.
5.3 Defeating the Feature Coding Method
A document to be feature coded would first be subjecl to
feature randomization prior to encoding. That IS.
character endline lengths would be randomly lengthened
or shortened, then altered again to ernbed a specific
codeword. Using this approach, the location of encoded
features can not be ascertained from Inspection of a
smgledocument, because the original endline lengths are
unknown. Of course, the encoded featwe Icxations can
be ascertained by obtaining two or inore distinctly
encoded, uncorrupted documents, and performing a page
by page pixel-wise difference operation on the
correspondingpage images.
It is interesting to note that a purely random
adjustment of endline lengths is not ;Iparticularly suong
attack on this coding technique. Yet feature encoding
can be defeated by using pixel processing tools to adjust
each endline length to a fixed value (e.g. the maximum
or minimum of the range of lengths observed in
multiple, distinctly marked copies ut a document). This
would obviously be painstaking to do manually.
particularly since the number of feature changes
introduced in a document can be large (e.g. 1 feature
change per word). This attack can be performed
automatically, however it can be made more challenging
by varying the particular feature to be encoded.
To conclude we note that even the most powerful
automated attacks can be somewhat 1rustr;ited by
introducing impediments within marked documents
designed primarily to increase their resistance to attack.
For example, word shifting might be used in addition to
feature coding, simply to frustmte an attackerâs attempts
to align corresponding pixels between two distinctly
encoded page images. Introducing enough of these
impediments to automated attacks might ensure tlhat
some manual intervention is required by the altacker.
Finally, note that possession of a document with
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10. markings either altered or removed indicates that the
document has been obtained illicitly. For many users
this is sufficient reason to obtain the document from the
legitimate source.
6. Summary
Making and disseminating illicit copies of documents
can be discouraged if each of the original copies is
unique, and can be associated with a particular recipient.
Several techniques for making text documents unique
have been described. One of these techniques, based on
text-line shifting, has been described in more detail. A
set of experiments was conducted to demonstrate that
small variations in line spacing indiscernible to a casual
reader can be recovered from a paper copy of the
document, even after being copied several times.
In our experiments, the position of the odd numbered
lines within each paragraph remained the same while the
even numbered lines were moved up or down by a small
,amount. By selecting different line shifts, information
was encoded into the document. To retrieve the
information from a paper copy, the document was
electronically scanned and analyzed. Two detection
methods were considered, one based on the location of
the bottom of the characters on each line, and the other
based on the center of mass of each line. The advantage
of using baselines is that they are equally spaced before
encoding and the information can be retrieved without
reference to a template. The centers of mass of the lines
are not equally spaced, however, this technique has been
found to be more resistant to the types of distortion
encountered in the printing and copying process.
The differential encoding mechanism was selected
because the types of distortion that have been
encountered have canceled out when differences
between adjacent lines are considered. In the
experiments, the lines in the document were moved up
or down by as little as 1/300 inch, the document was
copied as many as ten times, then the document was
scanned into a computer and decoded. For the set of
experiments that has been conducted, the centroid
decoding mechanism yielded an immeasurably small
error rate. Though experiments are ongoing, we beiieve
that sufficient data has been obtained to be convinced
that we can identify an intended recipient from a copy of
an encoded document as long as it remains legible.
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