This document discusses image enhancement techniques in the spatial domain. It introduces image enhancement and the spatial domain, which refers to direct pixel-level manipulation of the image plane. Various spatial domain operators and transformations are described, including gray-level transformations like negatives, log transformations, and power laws. Piecewise-linear transformations like thresholding, slicing, and bitplane slicing are also covered. The document discusses arithmetic, logic, and other operations that can be applied on sets of images and pixels. Histogram processing techniques like equalization are explained.
Spatial domain image enhancement techniques operate directly on pixel values. Some common techniques include point processing using gray level transformations, mask processing using filters, and histogram processing. Histogram equalization aims to create a uniform distribution of pixel values by mapping the original histogram to a wider range. This improves contrast by distributing pixels more evenly across gray levels.
Arithmetic coding is a lossless data compression technique that encodes data as a single real number between 0 and 1. It maps a string of symbols to a fractional number, with more probable symbols represented by larger fractional ranges. Encoding involves repeatedly dividing the interval based on symbol probabilities, and the final encoded number represents the entire string. Decoding reconstructs the string by comparing the number to symbol probability ranges. Arithmetic coding achieves compression closer to the entropy limit than Huffman coding by spreading coding inefficiencies across all symbols of the data.
Here in the ppt a detailed description of Image Enhancement Techniques is given which includes topics like Basic Gray level Transformations,Histogram Processing.
Enhancement using Arithmetic/Logic Operations.
image averaging and image averaging methods.
Piecewise-Linear Transformation Functions
This document discusses morphological image processing techniques. It begins by explaining that morphology uses mathematical morphology operations to extract image components and describe shapes. It then outlines common morphological algorithms like dilation, erosion, opening, closing, and hit-or-miss transformations. Dilation enlarges object boundaries while erosion shrinks them. Opening can smooth contours and closing can fuse breaks or fill gaps. These operations use a structuring element to transform images. The document provides examples of using morphological filters and algorithms for tasks like noise removal, region filling, and connected component extraction.
This document discusses different types of error free compression techniques including variable-length coding, Huffman coding, and arithmetic coding. It then describes lossy compression techniques such as lossy predictive coding, delta modulation, and transform coding. Lossy compression allows for increased compression by compromising accuracy through the use of quantization. Transform coding performs four steps: decomposition, transformation, quantization, and coding to compress image data.
This document discusses various techniques for enhancing images in the spatial domain, which involves direct manipulation of pixel values. It describes point processing techniques like gray-level transformations that map input pixel values to output values using functions like negative, logarithm, power-law, and piecewise linear. Histogram processing techniques are also covered, including histogram equalization, which spreads out the most frequent intensity values in an image. The document provides examples to illustrate the effect of these different enhancement methods.
The document discusses two algorithms for object detection: HOG and SIFT.
HOG (Histogram of Oriented Gradients) focuses on the shape of an object by using the magnitude and direction of gradients to generate histograms and compute features. SIFT (Scale Invariant Feature Transform) describes local image areas by extracting invariant features to generate a set of key points for matching objects across different scales and rotations. Both algorithms can be used to detect objects by matching image features to trained models.
This document provides an overview of image compression techniques. It defines key concepts like pixels, image resolution, and types of images. It then explains the need for compression to reduce file sizes and transmission times. The main compression methods discussed are lossless techniques like run-length encoding and Huffman coding, as well as lossy methods for images (JPEG) and video (MPEG) that remove redundant data. Applications of image compression include transmitting images over the internet faster and storing more photos on devices.
Spatial domain image enhancement techniques operate directly on pixel values. Some common techniques include point processing using gray level transformations, mask processing using filters, and histogram processing. Histogram equalization aims to create a uniform distribution of pixel values by mapping the original histogram to a wider range. This improves contrast by distributing pixels more evenly across gray levels.
Arithmetic coding is a lossless data compression technique that encodes data as a single real number between 0 and 1. It maps a string of symbols to a fractional number, with more probable symbols represented by larger fractional ranges. Encoding involves repeatedly dividing the interval based on symbol probabilities, and the final encoded number represents the entire string. Decoding reconstructs the string by comparing the number to symbol probability ranges. Arithmetic coding achieves compression closer to the entropy limit than Huffman coding by spreading coding inefficiencies across all symbols of the data.
Here in the ppt a detailed description of Image Enhancement Techniques is given which includes topics like Basic Gray level Transformations,Histogram Processing.
Enhancement using Arithmetic/Logic Operations.
image averaging and image averaging methods.
Piecewise-Linear Transformation Functions
This document discusses morphological image processing techniques. It begins by explaining that morphology uses mathematical morphology operations to extract image components and describe shapes. It then outlines common morphological algorithms like dilation, erosion, opening, closing, and hit-or-miss transformations. Dilation enlarges object boundaries while erosion shrinks them. Opening can smooth contours and closing can fuse breaks or fill gaps. These operations use a structuring element to transform images. The document provides examples of using morphological filters and algorithms for tasks like noise removal, region filling, and connected component extraction.
This document discusses different types of error free compression techniques including variable-length coding, Huffman coding, and arithmetic coding. It then describes lossy compression techniques such as lossy predictive coding, delta modulation, and transform coding. Lossy compression allows for increased compression by compromising accuracy through the use of quantization. Transform coding performs four steps: decomposition, transformation, quantization, and coding to compress image data.
This document discusses various techniques for enhancing images in the spatial domain, which involves direct manipulation of pixel values. It describes point processing techniques like gray-level transformations that map input pixel values to output values using functions like negative, logarithm, power-law, and piecewise linear. Histogram processing techniques are also covered, including histogram equalization, which spreads out the most frequent intensity values in an image. The document provides examples to illustrate the effect of these different enhancement methods.
The document discusses two algorithms for object detection: HOG and SIFT.
HOG (Histogram of Oriented Gradients) focuses on the shape of an object by using the magnitude and direction of gradients to generate histograms and compute features. SIFT (Scale Invariant Feature Transform) describes local image areas by extracting invariant features to generate a set of key points for matching objects across different scales and rotations. Both algorithms can be used to detect objects by matching image features to trained models.
This document provides an overview of image compression techniques. It defines key concepts like pixels, image resolution, and types of images. It then explains the need for compression to reduce file sizes and transmission times. The main compression methods discussed are lossless techniques like run-length encoding and Huffman coding, as well as lossy methods for images (JPEG) and video (MPEG) that remove redundant data. Applications of image compression include transmitting images over the internet faster and storing more photos on devices.
Histogram equalization is a method in image processing of contrast adjustment using the image's histogram. Histogram equalization can be used to improve the visual appearance of an image. Peaks in the image histogram (indicating commonly used grey levels) are widened, while the valleys are compressed.
Spatial domain filtering involves modifying an image by applying a filter or kernel to pixels within a neighborhood region. There are two main types of spatial filters - smoothing/low-pass filters which blur an image, and sharpening/high-pass filters which enhance edges and details. Smoothing filters replace each pixel value with the average of neighboring pixels, reducing noise. Sharpening filters use derivatives of Gaussian kernels to highlight areas of rapid intensity change, increasing contrast along edges. The effects of filtering depend on the size and shape of the kernel, with larger kernels producing more blurring or sharpening.
This document summarizes key concepts in morphological image processing including dilation, erosion, opening, closing, and hit-or-miss transformations. Morphological operations manipulate image shapes and structures using structuring elements based on set theory operations. Dilation adds pixels to the boundaries of objects in an image, while erosion removes pixels on object boundaries. Opening can remove noise and smooth object contours, while closing can fill in small holes and fill gaps in object shapes. Hit-or-miss transformations are used to detect specific patterns of on and off pixels. These operations form the basis for morphological algorithms like boundary extraction.
This document discusses techniques for image enhancement through spatial filtering. It begins with a refresher on spatial filtering, then discusses sharpening filters including 1st and 2nd derivative filters. The Laplacian filter is presented as a simple sharpening filter based on the 2nd derivative that highlights edges. Applying the Laplacian filter alone does not produce an enhanced image. To generate a sharpened image, the result of the Laplacian filter must be subtracted from the original image.
Digital Image Processing covers intensity transformations that can be performed on images. These include basic transformations like negatives, log transformations, and power-law transformations. It also discusses image histograms, which measure the frequency of each intensity level in an image. Histogram equalization aims to improve contrast by mapping intensities to produce a uniform histogram. It works by spreading out the most frequent intensity values.
This document provides an overview of digital image processing and image compression techniques. It defines what a digital image is, discusses the advantages and disadvantages of digital images over analog images. It describes the fundamental steps in digital image processing as well as types of data redundancy that can be exploited for image compression, including coding, interpixel, and psychovisual redundancy. Common image compression models and lossless compression techniques like Lempel-Ziv-Welch coding are also summarized.
This document discusses image histogram equalization. It begins by defining an image histogram as a graphical representation of the number of pixels at each intensity value. Histogram equalization automatically determines a transformation function to produce a new image with a uniform histogram and increased contrast. This technique works by mapping the intensity values of the input image to a new range of values such that the histogram of the output image is uniform. The document provides an example of performing histogram equalization on an image and assigns related homework on digital image processing applications.
Image enhancement techniques can be used to improve image visual appearance and analysis by accentuating features like edges and boundaries. There are several techniques including:
1. Point operations like contrast stretching and thresholding that modify pixel values.
2. Spatial operations like noise smoothing and sharpening that apply neighborhood pixel averaging or differencing.
3. Transform domain techniques like filtering in the frequency domain to accelerate operations like noise removal.
4. Edge enhancement methods like the pyramid approach that detects edges across multiple image scales to isolate significant edges.
This document provides an introduction to image segmentation. It discusses how image segmentation partitions an image into meaningful regions based on measurements like greyscale, color, texture, depth, or motion. Segmentation is often an initial step in image understanding and has applications in identifying objects, guiding robots, and video compression. The document describes thresholding and clustering as two common segmentation techniques and provides examples of segmentation based on greyscale, texture, motion, depth, and optical flow. It also discusses region-growing, edge-based, and active contour model approaches to segmentation.
This document discusses various point processing and gray level transformation techniques used in image enhancement. It describes point processing as operating directly on pixel intensity values individually to alter them using transformation functions. The document outlines several basic gray level transformations including linear, logarithmic and power law. It also discusses piecewise linear transformations such as contrast stretching, intensity level slicing, and bit plane slicing. These transformations are used to enhance images by modifying their brightness, contrast and emphasis on certain gray levels.
JPEG compression is a lossy compression technique that exploits human visual perception. It works by:
1) Splitting images into blocks and applying the discrete cosine transform (DCT) to each block to de-correlate pixel values.
2) Quantizing the resulting DCT coefficients, discarding less visible high-frequency data.
3) Entropy coding the quantized DCT coefficients using techniques like run-length encoding and Huffman coding to further compress the data.
A completed modeling of local binary pattern operatorWin Yu
This document presents the completed local binary pattern (CLBP) operator for texture classification. CLBP generalizes and completes the local binary pattern (LBP) by using a local difference sign-magnitude transform to encode the missing texture information not captured by LBP. The CLBP operator fuses three codes - CLBP_C for the center pixel, CLBP_S for the signs of differences, and CLBP_M for the magnitudes. Experiments on the Outex texture database show CLBP achieves much better classification accuracy than LBP and other state-of-the-art methods.
The document discusses various types of filters that can be used to reduce noise in digital images, including mean filters, median filters, and order statistics filters. Mean filters include arithmetic, geometric, and harmonic filters, which reduce noise by calculating the mean pixel value within a neighborhood. Median filters select the median pixel value within a neighborhood to reduce salt and pepper noise while retaining edges. Adaptive filters modify their behavior based on statistical properties of local regions in order to better reduce noise without excessive blurring.
Threshold Selection for Image segmentationParijat Sinha
1. The document examines different image segmentation techniques and threshold selection methods. It analyzes thresholding applied to images of rice grains and spots.
2. Global and adaptive thresholding techniques are compared, with adaptive thresholding found to better handle non-uniform backgrounds. Histogram peak and valley methods for optimal threshold selection are described.
3. Analyzing a spot image, adaptive thresholding at 50-75% best identified the spot, while other edge detectors like Roberts failed. Adaptive thresholding and spot profile analysis were concluded to best analyze spot images.
Sign Language Recognition using MediapipeIRJET Journal
This document summarizes a student research project that aims to develop a sign language recognition system using the Mediapipe framework. The system takes video input of signed letters from the American Sign Language alphabet and outputs the recognized letters in text format. The document provides background on sign language and gesture recognition, describes the Mediapipe framework and implementation methodology using KNN classification, and presents preliminary results of the system detecting hand positions and recognizing letters in real-time. The overall goal is to reduce communication barriers for deaf individuals by translating sign language to written text.
This document discusses noise in image processing and various methods for noise removal. It defines noise as unwanted signals that can corrupt an image's quality and originality. Common sources of noise include poor image sensors, lens defects, and low light levels. The document outlines different types of noises like Gaussian noise and impulse noise. It then describes various linear and non-linear filters that can be used for noise removal, such as averaging filters, Gaussian filters, median filters, and Wiener filters. The median filter is effective for salt and pepper noise while preserving edges. Adaptive filters can discriminate between corrupted and clean pixels for better noise removal.
This document discusses image enhancement techniques in the spatial domain. It begins by introducing intensity transformations and spatial filtering as the two principal categories of spatial domain processing. It then describes the basics of intensity transformations, including how they directly manipulate pixel values in an image. The document focuses on different types of basic intensity transformation functions such as image negation, log transformations, power law transformations, and piecewise linear transformations. It provides examples of how these transformations can be used to enhance images. Finally, it discusses histogram processing and how the histogram of an image provides information about the distribution of pixel intensities.
This document provides an overview of a research project on image compression. It discusses image compression techniques including lossy and lossless compression. It describes using discrete wavelet transform, lifting wavelet transform, and stationary wavelet transform for image transformation. Experiments were conducted to compare the compression ratio and processing time of different combinations of wavelet transforms, vector quantization, and Huffman/Arithmetic coding. The results were analyzed to evaluate the compression performance and efficiency of the different methods.
Digital Image Processing: Image Enhancement in the Spatial DomainMostafa G. M. Mostafa
This document discusses various image enhancement techniques in the spatial domain, including point operations, histogram equalization, and spatial filtering. Point operations include transformations like thresholding, negatives, power-law and gamma corrections that manipulate individual pixel intensities. Histogram equalization improves contrast by spreading out the most frequent intensity values. Spatial filtering techniques like smoothing, sharpening and edge detection use small filters to modify pixel values based on neighboring areas.
This document discusses various intensity transformation and spatial filtering techniques for digital image enhancement. It covers single pixel operations like negative image and contrast stretching. It also discusses neighborhood operations such as averaging and median filters. Finally, it discusses geometric spatial transformations like scaling, rotation and translation. The document provides details on basic intensity transformation functions including log, power law, and piecewise linear transformations. It also covers histogram processing techniques like histogram equalization, matching and local histogram processing. Spatial filtering and its mechanics are explained.
Histogram equalization is a method in image processing of contrast adjustment using the image's histogram. Histogram equalization can be used to improve the visual appearance of an image. Peaks in the image histogram (indicating commonly used grey levels) are widened, while the valleys are compressed.
Spatial domain filtering involves modifying an image by applying a filter or kernel to pixels within a neighborhood region. There are two main types of spatial filters - smoothing/low-pass filters which blur an image, and sharpening/high-pass filters which enhance edges and details. Smoothing filters replace each pixel value with the average of neighboring pixels, reducing noise. Sharpening filters use derivatives of Gaussian kernels to highlight areas of rapid intensity change, increasing contrast along edges. The effects of filtering depend on the size and shape of the kernel, with larger kernels producing more blurring or sharpening.
This document summarizes key concepts in morphological image processing including dilation, erosion, opening, closing, and hit-or-miss transformations. Morphological operations manipulate image shapes and structures using structuring elements based on set theory operations. Dilation adds pixels to the boundaries of objects in an image, while erosion removes pixels on object boundaries. Opening can remove noise and smooth object contours, while closing can fill in small holes and fill gaps in object shapes. Hit-or-miss transformations are used to detect specific patterns of on and off pixels. These operations form the basis for morphological algorithms like boundary extraction.
This document discusses techniques for image enhancement through spatial filtering. It begins with a refresher on spatial filtering, then discusses sharpening filters including 1st and 2nd derivative filters. The Laplacian filter is presented as a simple sharpening filter based on the 2nd derivative that highlights edges. Applying the Laplacian filter alone does not produce an enhanced image. To generate a sharpened image, the result of the Laplacian filter must be subtracted from the original image.
Digital Image Processing covers intensity transformations that can be performed on images. These include basic transformations like negatives, log transformations, and power-law transformations. It also discusses image histograms, which measure the frequency of each intensity level in an image. Histogram equalization aims to improve contrast by mapping intensities to produce a uniform histogram. It works by spreading out the most frequent intensity values.
This document provides an overview of digital image processing and image compression techniques. It defines what a digital image is, discusses the advantages and disadvantages of digital images over analog images. It describes the fundamental steps in digital image processing as well as types of data redundancy that can be exploited for image compression, including coding, interpixel, and psychovisual redundancy. Common image compression models and lossless compression techniques like Lempel-Ziv-Welch coding are also summarized.
This document discusses image histogram equalization. It begins by defining an image histogram as a graphical representation of the number of pixels at each intensity value. Histogram equalization automatically determines a transformation function to produce a new image with a uniform histogram and increased contrast. This technique works by mapping the intensity values of the input image to a new range of values such that the histogram of the output image is uniform. The document provides an example of performing histogram equalization on an image and assigns related homework on digital image processing applications.
Image enhancement techniques can be used to improve image visual appearance and analysis by accentuating features like edges and boundaries. There are several techniques including:
1. Point operations like contrast stretching and thresholding that modify pixel values.
2. Spatial operations like noise smoothing and sharpening that apply neighborhood pixel averaging or differencing.
3. Transform domain techniques like filtering in the frequency domain to accelerate operations like noise removal.
4. Edge enhancement methods like the pyramid approach that detects edges across multiple image scales to isolate significant edges.
This document provides an introduction to image segmentation. It discusses how image segmentation partitions an image into meaningful regions based on measurements like greyscale, color, texture, depth, or motion. Segmentation is often an initial step in image understanding and has applications in identifying objects, guiding robots, and video compression. The document describes thresholding and clustering as two common segmentation techniques and provides examples of segmentation based on greyscale, texture, motion, depth, and optical flow. It also discusses region-growing, edge-based, and active contour model approaches to segmentation.
This document discusses various point processing and gray level transformation techniques used in image enhancement. It describes point processing as operating directly on pixel intensity values individually to alter them using transformation functions. The document outlines several basic gray level transformations including linear, logarithmic and power law. It also discusses piecewise linear transformations such as contrast stretching, intensity level slicing, and bit plane slicing. These transformations are used to enhance images by modifying their brightness, contrast and emphasis on certain gray levels.
JPEG compression is a lossy compression technique that exploits human visual perception. It works by:
1) Splitting images into blocks and applying the discrete cosine transform (DCT) to each block to de-correlate pixel values.
2) Quantizing the resulting DCT coefficients, discarding less visible high-frequency data.
3) Entropy coding the quantized DCT coefficients using techniques like run-length encoding and Huffman coding to further compress the data.
A completed modeling of local binary pattern operatorWin Yu
This document presents the completed local binary pattern (CLBP) operator for texture classification. CLBP generalizes and completes the local binary pattern (LBP) by using a local difference sign-magnitude transform to encode the missing texture information not captured by LBP. The CLBP operator fuses three codes - CLBP_C for the center pixel, CLBP_S for the signs of differences, and CLBP_M for the magnitudes. Experiments on the Outex texture database show CLBP achieves much better classification accuracy than LBP and other state-of-the-art methods.
The document discusses various types of filters that can be used to reduce noise in digital images, including mean filters, median filters, and order statistics filters. Mean filters include arithmetic, geometric, and harmonic filters, which reduce noise by calculating the mean pixel value within a neighborhood. Median filters select the median pixel value within a neighborhood to reduce salt and pepper noise while retaining edges. Adaptive filters modify their behavior based on statistical properties of local regions in order to better reduce noise without excessive blurring.
Threshold Selection for Image segmentationParijat Sinha
1. The document examines different image segmentation techniques and threshold selection methods. It analyzes thresholding applied to images of rice grains and spots.
2. Global and adaptive thresholding techniques are compared, with adaptive thresholding found to better handle non-uniform backgrounds. Histogram peak and valley methods for optimal threshold selection are described.
3. Analyzing a spot image, adaptive thresholding at 50-75% best identified the spot, while other edge detectors like Roberts failed. Adaptive thresholding and spot profile analysis were concluded to best analyze spot images.
Sign Language Recognition using MediapipeIRJET Journal
This document summarizes a student research project that aims to develop a sign language recognition system using the Mediapipe framework. The system takes video input of signed letters from the American Sign Language alphabet and outputs the recognized letters in text format. The document provides background on sign language and gesture recognition, describes the Mediapipe framework and implementation methodology using KNN classification, and presents preliminary results of the system detecting hand positions and recognizing letters in real-time. The overall goal is to reduce communication barriers for deaf individuals by translating sign language to written text.
This document discusses noise in image processing and various methods for noise removal. It defines noise as unwanted signals that can corrupt an image's quality and originality. Common sources of noise include poor image sensors, lens defects, and low light levels. The document outlines different types of noises like Gaussian noise and impulse noise. It then describes various linear and non-linear filters that can be used for noise removal, such as averaging filters, Gaussian filters, median filters, and Wiener filters. The median filter is effective for salt and pepper noise while preserving edges. Adaptive filters can discriminate between corrupted and clean pixels for better noise removal.
This document discusses image enhancement techniques in the spatial domain. It begins by introducing intensity transformations and spatial filtering as the two principal categories of spatial domain processing. It then describes the basics of intensity transformations, including how they directly manipulate pixel values in an image. The document focuses on different types of basic intensity transformation functions such as image negation, log transformations, power law transformations, and piecewise linear transformations. It provides examples of how these transformations can be used to enhance images. Finally, it discusses histogram processing and how the histogram of an image provides information about the distribution of pixel intensities.
This document provides an overview of a research project on image compression. It discusses image compression techniques including lossy and lossless compression. It describes using discrete wavelet transform, lifting wavelet transform, and stationary wavelet transform for image transformation. Experiments were conducted to compare the compression ratio and processing time of different combinations of wavelet transforms, vector quantization, and Huffman/Arithmetic coding. The results were analyzed to evaluate the compression performance and efficiency of the different methods.
Digital Image Processing: Image Enhancement in the Spatial DomainMostafa G. M. Mostafa
This document discusses various image enhancement techniques in the spatial domain, including point operations, histogram equalization, and spatial filtering. Point operations include transformations like thresholding, negatives, power-law and gamma corrections that manipulate individual pixel intensities. Histogram equalization improves contrast by spreading out the most frequent intensity values. Spatial filtering techniques like smoothing, sharpening and edge detection use small filters to modify pixel values based on neighboring areas.
This document discusses various intensity transformation and spatial filtering techniques for digital image enhancement. It covers single pixel operations like negative image and contrast stretching. It also discusses neighborhood operations such as averaging and median filters. Finally, it discusses geometric spatial transformations like scaling, rotation and translation. The document provides details on basic intensity transformation functions including log, power law, and piecewise linear transformations. It also covers histogram processing techniques like histogram equalization, matching and local histogram processing. Spatial filtering and its mechanics are explained.
This document provides an overview of various image enhancement techniques. It begins with an introduction to image enhancement and its objectives. It then outlines and describes several categories of enhancement methods, including spatial-frequency domain methods, point operations, histogram operations, spatial operations, and transform operations. Specific techniques discussed in detail include contrast stretching, clipping, thresholding, median filtering, unsharp masking, and principal component analysis for multispectral images. The document also covers color image enhancement and techniques for pseudocoloring.
This presentation describes briefly about the image enhancement in spatial domain, basic gray level transformation, histogram processing, enhancement using arithmetic/ logical operation, basics of spatial filtering and local enhancements.
This document provides an overview of image enhancement techniques. It discusses the objectives of image enhancement, which is to process an image to make it more suitable for a specific application or task. The document focuses on spatial domain techniques for image enhancement, specifically point processing methods and histogram processing. It categorizes image enhancement methods into two broad categories: spatial domain methods, which directly manipulate pixel values; and frequency domain methods, which first convert the image into the frequency domain before performing enhancements.
Image enhancement using alpha rooting based hybrid techniqueRahul Yadav
The document proposes a hybrid technique for image enhancement combining alpha rooting, log transformation, and power law transformation. Alpha rooting is applied in the frequency domain to separate magnitude and phase coefficients, enhancing sharpness but darkening the image. The proposed method applies log and power law transforms after inverse transformation to eliminate tonal changes and improve contrast and brightness. Experimental results demonstrate the hybrid approach enhances images while avoiding darkening artifacts of conventional alpha rooting. In conclusion, the alpha rooting based hybrid technique provides image enhancement without limitations of prior transform domain methods.
04 image enhancement in spatial domain DIPbabak danyal
This document discusses various techniques for image enhancement in the spatial domain. It describes point processing which modifies individual pixel intensities based solely on their values. It also explains intensity transformation functions used for contrast adjustment like gamma correction, gray-level expansion and compression to expand or compress the dynamic range of pixels. Additionally, it covers piecewise-linear transformations and gray-level slicing to enhance images.
This document discusses methods for enhancing spatial features in images. It describes spatial filtering and convolution, which involve applying kernels or filters to images to emphasize different spatial frequencies. Low-pass filters smooth images by reducing high spatial frequencies related to fine detail, while high-pass filters have the opposite effect of sharpening images. Edge enhancement filters aim to highlight linear features by increasing contrast around edges. Fourier analysis represents images as combinations of sine and cosine waves of different frequencies and can reveal features aligned in various directions.
COM2304: Intensity Transformation and Spatial Filtering – II Spatial Filterin...Hemantha Kulathilake
At the end of this lecture, you should be able to;
describe the fundamentals of spatial filtering.
generating spatial filter masks.
identify smoothing via linear filters and non linear filters.
apply smoothing techniques for problem solving.
This document discusses image restoration techniques for noise removal, including:
- Spatial domain filtering techniques like mean, median, and order statistics filters to remove random noise.
- Frequency domain filtering like band reject filters to remove periodic noise.
- Adaptive filtering techniques where the filter size changes depending on image characteristics within the filter region to better handle impulse noise.
Digital Image Processing: Image Enhancement in the Frequency DomainMostafa G. M. Mostafa
This document is a chapter from a textbook on digital image processing. It discusses the discrete Fourier transform (DFT) and its properties. It also covers various filtering techniques that can be performed in the frequency domain, including low-pass, high-pass, band-pass, and homomorphic filters using approaches like Gaussian, Butterworth, and ideal filters. Homework problems 4.9 and 4.12 are also mentioned at the end.
The document discusses various image enhancement techniques in digital image processing. It describes point operations like image negative, contrast stretching, thresholding, brightness enhancement, log transformation, and power law transformation. Contrast stretching expands the range of intensity levels and can be done by multiplying pixels with a constant, using a transfer function, or histogram equalization. Thresholding converts an image to binary by assigning pixel values above a threshold to one level and below to another. Log and power law transformations compress high intensity values and expand low values to enhance an image. Matlab code examples are provided for each technique.
- The document provides fishery escapement and survey information for the Wood River, Nushagak River, and Igushik River in Alaska on June 25th.
- Wood River sockeye escapements reached 85,000 and Nushagak escapements were 120,000 with additional fish counted.
- Aerial surveys found some sockeye in the lower rivers but visibility was limited.
- No test fish or CPUE information was available and high tide is scheduled for 7:00 pm on June 25th and 8:00 am on June 26th.
The document discusses using Fitbit devices in a high school classroom to motivate students towards healthier lifestyles. It includes an email exchange where a teacher asks questions about checking out a Fitbit to students and whether data supports their effectiveness. The Fitbit representative says the devices can be reset and checked out to multiple students. They also say Fitbits should not be used for contact sports but are fine for other activities like running. No free devices or rentals are offered but there is a 30-day return policy.
This document discusses three waves of computing: the Internet, mobile, and social. For each wave, it identifies the early enabling technologies and inherent advantages. It then discusses how massive amounts of data can be handled through teams of generalists and specialists. Finally, it suggests that future advantages will come from being able to process and act on available data through connected devices and software.
This document is a magazine published by Noa Noa that explores romance and fashion. It introduces their new Autumn/Winter collection and Noa Noa Décor home line. The magazine provides looks from the clothing line, styling tips from the design team, and previews pieces for the season ahead. It aims to bring the soul of the Noa Noa brand into readers' lives.
Measuring the Influence of Tag Recommenders on the Indexing Quality in Taggin...Klaas Dellschaft
This presentation is about our paper which was presented at the Hypertext conference 2012. In this paper, we investigate a methodology for measuring the influence of tag recommenders on the indexing quality in collaborative tagging systems. We propose to use the inter-resource consistency as an indicator of indexing quality. The inter-resource consistency measures the degree to which the tag vectors of indexed resources reflect how the users understand the resources. We use this methodology for evaluating how tag recommendations coming from (1) the popular tags at a resource or from (2) the user's own vocabulary influence the indexing quality. We show that recommending popular tags decreases the indexing quality and that recommending the user's own vocabulary increases the indexing quality.
Links to the paper:
http://dx.doi.org/10.1145/2309996.2310009
http://www.west.uni-koblenz.de/files/publications/dellschaft2012mti.pdf
This document appears to be a collection of messages between two friends, Shivani and Kiran, reminiscing about their friendship over the years. They discuss inside jokes and memories from their time in college, their shared interests and dislikes, how their first impressions of each other changed, conflicts they have overcome, and the important role they play in each other's lives. Kiran wishes Shivani a happy birthday and says he will celebrate with her next year.
A talk I gave on OpenSourceChina conference in Dec 2015. The talk is about how netflix builds its data pipeline platform to handle hundreds of billions of events a day. How everybody should leverage the same streaming architecture to build their apps.
Digital image enhancement involves modifying images to improve visual quality. It can be done in the spatial or frequency domain. Spatial domain enhancement works directly with pixel values. Key point processing techniques in the spatial domain include: digital negative, contrast stretching, thresholding, gray level slicing, bit plane slicing, and dynamic range compression. These techniques apply mathematical transforms to pixel values to darken or lighten regions of the image for better visualization.
Intensity Transformation and Spatial filteringShajun Nisha
Dr. S. Shajun Nisha discusses intensity transformation and spatial filtering techniques in image processing. Intensity transformation functions modify pixel intensities based on a transformation function. Spatial filtering involves applying an operator over a neighborhood of pixels. Common intensity transformations include contrast stretching and logarithmic transforms. Histogram equalization is also described to improve contrast. Spatial filters include linear filters implemented using imfilter and non-linear filters like median filtering with ordfilt2 and medfilt2. Examples demonstrate applying these techniques to enhance images.
This document provides an introduction to the basics of MATLAB. It discusses where to find help in MATLAB, how to work with matrices and perform basic operations on them. It also covers logical conditions, different types of loops (for, while, if/else), how to create scripts and functions. Finally, it provides an overview of visualization and graphics in MATLAB as well as an introduction to the image processing toolbox.
This document discusses spatial operations in image processing, including mathematical operations, spatial transformations, and intensity assignment. It covers array and matrix operations, linear and nonlinear operations, and basic arithmetic operations between images like addition, subtraction, multiplication and division. Spatial transformations include affine transforms that map pixel coordinates from one image to another. Intensity assignment is done through forward mapping, which can result in holes, or backward/inverse mapping, which interpolates intensities more efficiently.
This document discusses various techniques for image enhancement in spatial domain. It defines image enhancement as improving visual quality or converting images for better analysis. Key techniques covered include noise removal, contrast adjustment, intensity adjustment, histogram equalization, thresholding, gray level slicing, and image rotation. Conversion methods like grayscale and different file formats are also summarized. Experimental results and applications in fields like medicine, astronomy, and security are mentioned.
This document discusses image processing and digital images. It covers topics like:
- How images can be represented as functions that map pixel locations to intensity values.
- The process of sampling and quantizing to convert a continuous image into a digital image represented as a matrix of integer values.
- Different types of image processing operations including point processing that transform pixel values independently and neighborhood processing that considers pixel locations.
- Specific point processing techniques like negative, log transformations, and gamma correction.
- Image enhancement methods like contrast stretching, histograms, and histogram equalization.
This document discusses various techniques for image enhancement, including point operations, mask operations, transform operations, and coloring operations. It provides details on techniques such as contrast stretching, histogram equalization, and histogram specification. Histogram equalization aims to produce an output image with a uniform histogram, while histogram specification allows specifying a desired output histogram. Both techniques involve transforming the input image using the cumulative distribution function of the input pixel values.
The document discusses point processing operations in image processing which perform transformations independently on each pixel without considering spatial information. Point processing includes operations like negative, log, power-law transformations, and gamma correction that define a new image as a function of the existing image applied to each pixel. While point processing loses all spatial information, it can be used for basic image enhancement tasks like contrast stretching, histogram equalization, and matching.
This document discusses various techniques for enhancing images in the spatial domain, which involves direct manipulation of pixel values. It describes point processing techniques like gray-level transformations that map input pixel values to output values using functions like negative, logarithm, power-law, and piecewise linear. Histogram processing techniques are also covered, including histogram equalization, which spreads out the most frequent intensity values in an image. The document provides examples to illustrate the effect of these different enhancement methods.
Image Processing using Matlab . Useful for beginners to learn Image ProcessingAshok Kumar
Matlab can be used for image processing tasks such as loading, displaying, and manipulating images. Images are represented as matrices where each element corresponds to the pixel intensity values. Common operations include convolutions using various kernel filters to perform tasks like smoothing, sharpening, and edge detection. Functions such as imread, image, and imshow can load and display images. Built-in functions such as fspecial generate common kernel filters. Convolution functions convolve images with kernels to apply filtering effects.
The document discusses various image enhancement techniques in the spatial domain. It covers basic gray level transformations like negatives, log transformations, and power law transformations. It also discusses histogram processing and enhancement using arithmetic operations. Furthermore, it explains smoothing and sharpening spatial filters, and how to combine different spatial enhancement methods. The document provides examples and background on these fundamental image enhancement concepts.
This document provides an overview of key concepts in digital image fundamentals. It discusses the human visual system and image formation in the eye. It also covers image acquisition, sampling, quantization, and representation. Additionally, it defines concepts like spatial and intensity resolution and describes basic image processing operations and transforms. The goal is to introduce fundamental digital image processing concepts.
This document discusses various mathematical tools used in digital image processing (DIP), including array versus matrix operations, linear versus nonlinear operations, arithmetic operations, set and logical operations, spatial operations, vector and matrix operations, and image transforms. Key points include:
- Array operations are performed on a pixel-by-pixel basis, while matrix operations consider relationships between pixels.
- Linear operators preserve scaling and addition properties, while nonlinear operators like max do not.
- Spatial operations include single-pixel, neighborhood, and geometric transformations of pixel locations and intensities.
- Images can be represented as vectors and transformed using matrix operations.
- Common transforms like Fourier use separable, symmetric kernels to decompose images into frequency domains.
This document discusses image enhancement techniques in the spatial domain. It describes two categories of spatial domain operations: point processing and neighborhood processing. Point processing involves direct manipulation of pixel values through techniques like contrast stretching and thresholding. Neighborhood processing considers pixels in a local region and applies techniques like averaging filters. The document outlines several gray level transformations for enhancement, including logarithmic, power-law, piecewise linear, and bit-plane slicing transformations. It also discusses arithmetic and logic operations on images.
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The document discusses various intensity transformation techniques in digital image processing, including:
1. Contrast stretching, which darkens intensities below a threshold and brightens those above to increase contrast.
2. Logarithmic and power-law (gamma) transformations, which compress high intensities and enhance low intensities to adjust dynamic range.
3. Piecewise linear transformations, which can be used for contrast stretching, intensity level slicing to highlight regions, and bit-plane slicing for image compression and analysis.
4. Histogram equalization, which spreads intensity levels across the full range to improve contrast by flattening and spreading out the histogram. Histogram specification can modify the histogram to achieve a desired transformation.
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
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There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Main Java[All of the Base Concepts}.docxadhitya5119
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This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
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.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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2. Most of these slides base on the
book
Digital Image Processing
by Gonzales/Woods
Chapter 3
3. Introduction
Image Enhancement ?
• enhance otherwise hidden information
• Filter important image features
• Discard unimportant image features
Spatial Domain ?
• Refers to the image plane (the ‘natural’
image)
• Direct image manipulation
4. Remember ?
A 2D grayvalue - image is a 2D -> 1D
function,
v = f(x,y)
5. Remember ?
As we have a function, we can apply
operators to this function, e.g.
T(f(x,y)) = f(x,y) / 2
Operator Image (= function !)
6. Remember ?
T transforms the given image f(x,y)
into another image g(x,y)
f(x,y) g(x,y)
7. Spatial Domain
The operator T can be defined over
• The set of pixels (x,y) of the image
• The set of ‘neighborhoods’ N(x,y) of
each pixel
• A set of images f1,f2,f3,…
8. Spatial Domain
Operation on the set of image-pixels
6 8 2 0 3 4 1 0
12 200 20 10 6 100 10 5
(Operator: Div. by 2)
9. Spatial Domain
Operation on the set of ‘neighborhoods’
N(x,y) of each pixel
6 8 (Operator: sum)
12 200
6 8 2 0 226
12 200 20 10
10. Spatial Domain
Operation on a set of images f1,f2,…
6 8 2 0
12 200 20 10
(Operator: sum) 11 13 3 0
14 220 23 14
5 5 1 0
2 20 3 4
11. Spatial Domain
Operation on the set of image-pixels
Remark: these operations can also be seen as operations on the
neighborhood of a pixel (x,y), by defining the neighborhood as the
pixel itself.
• The simplest case of operators
• g(x,y) = T(f(x,y)) depends only on the value
of f at (x,y)
• T is called a
gray-level or intensity transformation
function
12. Transformations
Basic Gray Level Transformations
• Image Negatives
• Log Transformations
• Power Law Transformations
• Piecewise-Linear Transformation
Functions
For the following slides L denotes the max. possible gray value of the
image, i.e. f(x,y) ∈ [0,L]
22. Piecewise Linear Transformations
Thresholding Function
g(x,y) = L if f(x,y) > t,
0 else
t = ‘threshold level’
Output gray level
Input gray level
23. Piecewise Linear Transformations
Gray Level Slicing
Purpose: Highlight a specific range of grayvalues
Two approaches:
7. Display high value for range of interest, low value
else (‘discard background’)
9. Display high value for range of interest, original
value else (‘preserve background’)
27. Piecewise Linear Transformations
Exercise:
• How does the transformation
function look for bitplanes
0,1,… ?
• What is the easiest way to filter a single bitplane
(e.g. in MATLAB) ?
28. Histograms
Histogram Processing
1 4 5 0
3 1 5 1
Number of Pixels
gray level
29. Histograms
Histogram Equalization:
• Preprocessing technique to
enhance contrast in ‘natural’
images
• Target: find gray level
transformation function T to
transform image f such that the
histogram of T(f) is ‘equalized’
30. Histogram Equalization
Equalized Histogram:
The image consists of an equal
number of pixels for every gray-
value, the histogram is constant !
32. Histogram Equalization
Target:
Find a transformation T to transform the
grayvalues g1∈[0..1] of an image I to
grayvalues g2 = T(g1) such that the
histogram is equalized, i.e. there’s an
equal amount of pixels for each grayvalue.
Observation (continous model !):
Assumption: Total image area = 1 (normalized). Then:
The area(!) of pixels of the transformed
image in the gray-value range 0..g2 equals
the gray-value g2.
33. Histogram Equalization
The area(!) of pixels of the transformed image in the gray-
value range 0..g2 equals the gray-value g2.
⇒ Every g1 is transformed to a grayvalue
that equals the area (discrete: number of
pixels) in the image covered by pixels
having gray-values from 0 to g1.
⇒ The transformation T function t is the
area- integral: T: g2 = ∫ 0..g1 I da
34. Histogram Equalization
Discrete:
g1 is mapped to the (normalized)
number of pixels having
grayvalues 0..g1 .
35. Histogram Equalization
Mathematically the transformation
is deducted by theorems in
continous (not discrete) spaces.
The results achieved do NOT hold
for discrete spaces !
(Why ?)
However, it’s visually close.
36. Histogram Equalization
Conclusion:
• The transformation function that yields an image
having an equalized histogram is the integral of
the histogram of the source-image
• The discrete integral is given by the cumulative sum,
MATLAB function: cumsum()
• The function transforms an image into an image,
NOT a histogram into a histogram ! The
histogram is just a control tool !
• In general the transformation does not create an
image with an equalized histogram in the
discrete case !
37. Operations on a set of images
Operation on a set of images f1,f2,…
6 8 2 0
12 200 20 10
(Operator: sum) 11 13 3 0
14 220 23 14
5 5 1 0
2 20 3 4
38. Operations on a set of images
Logic (Bitwise) Operations
AND
OR
NOT
39. Operations on a set of images
The operators AND,OR,NOT are
functionally complete:
Any logic operator can be implemented
using only these 3 operators
40. Operations on a set of images
Any logic operator can be implemented
using only these 3 operators:
A B Op
0 0 1 Op=
NOT(A) AND NOT(B)
0 1 1
OR
1 0 0
NOT(A) AND B
1 1 0
41. Operations on a set of images
Image 1 AND Image 2
1 2 3 9
7 3 6 4
(Operator: AND) 1 0 1 1
2 2 2 0
1 1 1 1
2 2 2 2
42. Operations on a set of images
Image 1 AND Image 2:
Used for Bitplane-Slicing and
Masking
43. Operations on a set of images
Exercise: Define the mask-image, that
transforms image1 into image2 using
the OR operand
1 2 3 9
7 3 6 4
(Operator: OR) 255 2 7 255
255 3 7 255
44. Operations
Arithmetic Operations on a set of images
1 2 3 9
7 3 6 4
(Operator: +) 2 3 4 10
9 5 8 6
1 1 1 1
2 2 2 2
45. Operations
Exercise:
What could the operators +
and – be used for ?
49. Histograms
So far (part 1) :
• Histogram definition
• Histogram equalization
Now:
• Histogram statistics
50. Histograms
Remember:
The histogram shows the number of
pixels having a certain gray-value
number of pixels
grayvalue (0..1)
51. Histograms
The NORMALIZED histogram is the
histogram divided by the total number
of pixels in the source image.
The sum of all values in the normalized
histogram is 1.
The value given by the normalized
histogram for a certain gray value can
be read as the probability of randomly
picking a pixel having that gray value
52. Histograms
What can the (normalized)
histogram tell about the
image ?
53. Histograms
• The MEAN VALUE (or average gray level)
M = Σ g h(g)
g
1*0.3+2*0.1+3*0.2+4*0.1+5*0.2+6*0.1=
0.3
0.2 2.6
0.1
0.0
1 2 3 4 5 6
54. Histograms
The MEAN value is the average gray
value of the image, the ‘overall
brightness appearance’.
55. Histograms
2. The VARIANCE
V = Σ (g-M)2 h(g)
g
(with M = mean)
or similar:
The STANDARD DEVIATION
D = sqrt(V)
56. Histograms
VARIANCE gives a measure about the
distribution of the histogram values
around the mean.
0.3 0.3
0.2 0.2
0.1 0.1
0.0 0.0
V1 > V2
57. Histograms
The STANDARD DEVIATION is a value
on the gray level axis, showing the
average distance of all pixels to the
mean
0.3 0.3
0.2 0.2
0.1 0.1
0.0 0.0
D1 > D2
58. Histograms
VARIANCE and STANDARD DEVIATION
of the histogram tell us about the
average contrast of the image !
The higher the VARIANCE (=the higher
the STANDARD DEVIATION), the
higher the image’s contrast !
60. Histograms
Histograms with MEAN and
STANDARD DEVIATION
M=0.73 D=0.32 M=0.71 D=0.27
61. Histograms
Exercise:
Design an autofocus system for a digital
camera !
The system should analyse an area in the middle of the picture and
automatically adjust the lens such that this area is sharp.
62. Histograms
In between the basics…
…histograms can give us a first hint
how to create image databases:
63. Feature Based Coding
Feature Based Coding
• Determine a feature-vector for a given image
• Compare images by their feature-vectors
Two operations need to be defined: a mapping of shape
into the feature space and a similarity of feature vectors.
Representation Feature Extraction Vector Comparison
Where are the histograms ?
64. Feature Based Coding
Feature Based Coding
• Determine a feature-vector for a given image
• Compare images by their feature-vectors
Two operations need to be defined: a mapping of shape
into the feature space and a similarity of feature vectors.
Representation HISTOGRAM Histogram Comp.
HERE !
Question: how can we compare histograms (vectors) ?
68. Vector Comparison
What’s the meaning of the Cosine Distance with
respect to histograms ?
i.e.: what’s the consequence of eliminating the vector’s length information ?
69. Vector Comparison
More Vector Distances:
• Quadratic Form Distance
• Earth Movers Distance
• Proportional Transportation Distance
•…
70. Vector Comparison
Histogram Intersection
(non symmetric):
d(h1,h2) = 1 - ∑ min(h1 ,h2 )
i i i
/ ∑i h1i
Ex.: What could be a huge drawback of image
comparison using histogram intersection ?