Basics of Multimedia Technology• Multimedia is media and content that uses a combination of different content forms.• Multimedia includes a combination of text, audio, still images, animation, video, or interactivity content forms.• Basic multimedia and communications technology are two terms, which can be said to go hand in hand with each other. For instance, multimedia is a means of communication and communication relies on aspects of multimedia as the basis of its existence.Basic Multimedia• Basic multimedia refers to a number of varied technologies that allow both visual and audio media to be combined in new ways for the purpose of communicating. The term multimedia often refers to computer technologies and its applications include entertainment, education and advertising.• The majority of PC’s constructed today are capable of multimedia as they include a CD-ROM or DVD drive and possess a good sound and video card which is often built into the motherboard.• The term multimedia also describes a number of dedicated media appliances such as MP3 players, digital video recorders (DVR’s), advanced wireless devices, public video displays and interactive television.
Communications Technology• Communication with regards to computing world refers to the transmission of data from one computer to another from one device to another.• A communications device therefore is any machine that assists data transmission. Examples of communication devices include modems cables and ports.• Programs, which allow transmission of data, are known as communications software. Therefore communications technology refers to the activity of designing and constructing and maintaining communication systems
Computer• A computer is a programmable machine. The two principal characteristics of a computer are: it responds to a specific set of instructions in a well- defined manner and it can execute a prerecorded list of instructions (a program).Modern Computers DefinedModern computers are electronic and digital. The actual machinery -- wires,transistors, and circuits -- is called hardware; the instructions and data are called software.• All general-purpose computers require the following hardware components:• memory: enables a computer to store, at least temporarily, data and programs.• mass storage device: allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.• input device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.• output device: a display screen, printer, or other device that lets you see what the computer has accomplished.• central processing unit (CPU): the heart of the computer, this is the component that actually executes instructions.
communication and entertainmentWhat is communication:-• Art of getting your message across effectively through:• Spoken words-first & simplest way• Body language-can make or mar• Written words-reflects importance• Visuals-leaves greatest impact
Multimedia an introduction• Multimedia comes in many different formats. It can be almost anything you can hear or see.• Examples: Pictures, music, sound, videos, records, films, animations, and more.
Multimedia- Definitions • Multimedia is any combination of digitally manipulated text, art, sound, animation and video. • A more strict version of the definition of multimedia do not allow just any combination of media. • It requires – Both continuous & discrete media to be utilized – Significant level of independence between media being used • The less stricter version of the definition is used in practice.Multimedia I -2009 Mohammed Dwikat 8
Multimedia- Definitions• Multimedia elements are composed into a project using authoring tools.• Multimedia Authoring tools are those programs that provide the capability for creating a complete multimedia presentations by linking together objects such as a paragraph of text (song), an illustration, an audio, with appropriate interactive user control.Multimedia I -2009 Mohammed Dwikat 9
Framework for multimedia systemsMultimedia Framework Overview• Multimedia architecture• QNX-provided components• Extending functionalityMultimedia architecture• The Multimedia library architecture is modular, meaning that it consists of units that can be interchanged with each other to provide only the functionality you need.• Each filter can have multiple input and output channels, so if you have a file format thats interleaved with more than one data stream, you can have as many output data channels as the input data stream contains.
The Multimedia library offers these benefits:• In most cases it doesnt require hardware with an FPU to deliver acceptable performance (although hardware with an FPU may deliver better performance).• Its modular design means you include only the media elements you need in your application, which reduces size and complexity.• It allows you to easily write your own codecs to deal with new multimedia data formats, or to rewrite or replace existing codecs.• It can be optimized for memory or CPU performance to suit a wide variety of hardware.• It can handle both frame-based (such as MPEG-1 audio) and streaming (such as MPEG video) data streams.• Its designed with a simple, intuitive API.
Multimedia DevicesWebcam• A webcam is a simple digital camera capable of taking video or still images for transmission over the Internet. Unlike digital cameras (next section), webcams don’t include storage capabilities.Most webcams plug into a USB port, but a few have used IEEE 1394 or parallel ports.Digital Camera• Digital cameras have largely replaced film cameras for both amateur and professional photography.• Digital cameras transfer images to computers for emailing, printing, or storage via either flash memory card readers or direct USB port connections.MIDI Music and MIDI Ports• Musical instrument digital interface (MIDI) music is created from digitized samples of musical instruments that are stored in the ROM or RAM of a MIDI device (such as a sound card) and played under the command of a MIDI sequencer. MIDI sequences can be stored as files for future playback, and can be transferred between sound cards and MIDI-enabled devices such as keyboards via the MIDI port.
• Sound CardSound cards are used to record and play back analog audio, and most can also play back digital audio sources as well. When recording analog audio sources such as CDs, line in or microphone in, sound cards digitize the audio at varying sample rates and store files in either uncompressed forms such as WAV or compressed forms such as WMA or MP3.
Delivering mediumCD-ROM• It is also an optical storage and considered the most common form of packaging for multimedia products.• It started out as a read-only technology in which user could store data once only and access it many times.• Recent technology led to a multi-session version where user can add to the content of a CD and even fully able to write to the systems.
• CD-ROMs are popularly used to distribute computer software, including video games and multimedia applications, though any data can be stored (up to the capacity limit of a disc).• Some CDs hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). These are called enhanced CDs.
• The Philips CD-i (Compact Disc Interactive) is an interactive multimedia CD player developed and marketed by Royal Philips Electronics N.V.• This category of device was created to provide more functionality than an audio CD player or game console, but at a lower price than a personal computer with CD- ROM drive at the time.• The cost savings were due to the lack of a hard drive, floppy drive, keyboard, mouse, monitor (a standard television was used), and less operating system software.
The user interface• System users often judge a system by itsinterface rather than its functionality• A poorly designed interface can cause a user to make catastrophic errors• Poor user interface design is the reason why so many software systems are never usedGraphical user interfaces• Most users of business systems interact with these systems through graphical interfaces although, in some cases, legacy text-based interfaces are still used
2.1 Multimedia Authoring• Multimedia authoring: creation of multimedia productions, sometimes called “movies” or “presentations”. – we are mostly interested in interactive applications. – For practicality, we also have a look at still-image editors such as Adobe Photoshop, and simple video editors such as Adobe Premiere.• In this section, we take a look at: – Multimedia Authoring Metaphors – Multimedia Production – Multimedia Presentation – Automatic Authoring Multimedia Systems (firstname.lastname@example.org) 18
Multimedia Authoring Metaphors1. Scripting Language Metaphor: use a special language to enable interactivity (buttons, mouse, etc.), and to allow conditionals, jumps, loops, functions/macros etc. E.g., a small Toolbook program is as below: -- load an MPEG file extFileName of MediaPlayer "theMpegPath" = "c:windowsmediahome33.mpg"; -- play extPlayCount of MediaPlayer "theMpegPath" = 1; -- put the MediaPlayer in frames mode (not time mode) extDisplayMode of MediaPlayer "theMpegPath" = 1; -- if want to start and end at specific frames: extSelectionStart of MediaPlayer "theMpegPath" = 103; extSelectionEnd of MediaPlayer "theMpegPath" = 1997; -- start playback get extPlay() of MediaPlayer "theMpegPath"; Multimedia Systems (email@example.com) 19
2. Slide Show Metaphor: A linear presentation by default, although tools exist to perform jumps in slide shows.3. Hierarchical Metaphor: User-controllable elements are organized into a tree structure — often used in menu-driven applications.4. Iconic/Flow-control Metaphor: Graphical icons are available in a toolbox, and authoring proceeds by creating a flow chart with icons attached (Fig. 2.1): Multimedia Systems (firstname.lastname@example.org) 20
5. Frames Metaphor: Like Iconic/Flow-control Metaphor; however links between icons are more conceptual, rather than representing the actual flow of the program (Fig. 2.2): Fig. 2.2: Quest Frame Multimedia Systems (email@example.com) 21
6. Card/Scripting Metaphor: Uses a simple index-card structure — easy route to producing applications that use hypertext or hypermedia; used in schools. Fig. 2.3: Two Cards in a Hypermedia Stack Multimedia Systems (firstname.lastname@example.org) 22
7. Cast/Score/Scripting Metaphor: • Time is shown horizontally; like a spreadsheet: rows, or tracks, represent instantiations of characters in a multimedia production. • Multimedia elements are drawn from a cast of characters, and scripts are basically event-procedures or procedures that are triggered by timer events. • Director, by Macromedia, is the chief example of this metaphor. Director uses the Lingo scripting language, an object-oriented event-driven language. Multimedia Systems (email@example.com) 23
Uses of multimedia authoring programs• Create multimedia titles• Create interactivity• Design screen layouts• Produce content with paint, text, and animation tools• Incorporate text, sound, video, animation, and graphics• Create hyperlinks
Types of Multimedia Authoring ProgramsAuthoring programs are categorized mainly by the way they work.• Electronic slide show • Card/book metaphor Advantages: Advantages: • Inexpensive to create • Easy to learn • Easy to use • Direct relationship between what is on a • Easy to learn card or page and what • Templates available is displayed on a screen. that can be customized Disadvantages: Disadvantage: • Usually run on one platform Predominately linear presentations • Usually limited compared to other authoring programs.
Types of Multimedia Authoring Programs (Continued)• Icon-based authoring • Time-based authoring programs use programs are like flowchart to represent movies that play until content or event. some action causes it to stop. Advantage: Flow of content or event Advantage: easily seen. Disadvantages: Users can branch to • Less insightful different parts of • Difficult to learn movies • Expensive
• Uses of multimedia authoring programs Create multimedia titles Create interactivity Design screen layouts Produce content with paint, text, and animation tools Incorporate text, sound, video, animation, and graphics Create hyperlinks• Types of multimedia authoring programs Electronic slide show Card/book metaphor Icon-based Time-based Web-based Programming languages
Professional development tools• WebinarsOrganizations that deliver webinars on topics relevant to SNAP-Ed providers.• CalendarUpcoming Conference Calendar• Online TrainingOnline training resources, including modules and courses, for nutrition educators.• Conference ProceedingsSelected highlights from recent conferences. Materials are either from SNAP-Ed specific sessions or are applicable to SNAP-Ed providers.• Icebreakers and Training ToolsResources for SNAP-Ed providers working in group settings.• Social MarketingDefinitions, overviews, examples, research, guides and other resources on social marketing.• EvaluationResources for developing and conducting evaluations of nutrition education programs.• Behavior ChangeReports and articles for educators working to promote behavior change.
Local Area Networks (LANs)• In IEEE 802 Reference Model for LANs, the functionality of the Data Link layer is enhanced, and it has been divided into two sublayers: – - Medium Access Control (MAC) layer: (a) Assemble or disassemble frames upon transmission or reception. (b) perform addressing and error correction. (c) Access control to shared physical medium. – - Logical Link Control (LLC) layer: (a) Flow and error control. (b) MAC-layer addressing. (c) Interface to higher layers. LLC is above MAC in the hierarchy. Li & Drew 29
Internt• The Internet (or internet) is a global system of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users worldwide.• It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies.
World wide web• The World Wide Web (abbreviated as WWW or W3, commonly known as the Web), is a system of interlinked hypertext documents accessed via the Internet.• The documents are formatted in a markup language called HTML (HyperText Markup Language) that supports links to other documents, as well asgraphics, audio, and video files.• This means you can jump from one document to another simply by clicking on hot spots. Not all Internet servers are part of the World Wide Web.• World Wide Web is not synonymous with the Internet.
The Asynchronous Transfer Mode• (ATM) (ATM) is, according to the ATM Forum, "a telecommunications concept defined by ANSI and ITU (formerly CCITT) standards for carriage of a complete range of user traffic, including voice, data, and video signals,“• ATM provides data link layer services that run over a wide range of OSI physical Layer links. ATM has functional similarity with both circuit switched networking and small packet switched networking.• ATM is a technology that provides a single platform for the transmission of voice, video, and data at specified quality of service and at speeds varying from fractional T1, i.e., nX64 Kbps, to Gbps. Voice, data and video are currently transported by different networks.
(ADSL)• Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are not used by a voicetelephone call.• At the telephone exchange the line generally terminates at a digital subscriber line access multiplexer (DSLAM) where another frequency splitter separates the voice band signal for the conventional phone network.• Data carried by the ADSL are typically routed over the telephone companys data network and eventually reach a conventional Internet Protocol network.
ADSL is:■ Asymmetric, because data transmission is faster downstream to the subscriber than upstream from the subscriber,■ Digital, because even voice and video are digitised before they are transmitted as modulated analogue representations of digital data,■ Subscriber Line, because data is carried over a single twisted pair copper ‘loop’ to the subscribers premises.Why use ADSL? Typically Web browsing involves downloading five times as much data as ittransmits, so customers do not need a high bi-directional transmission speed.ADSL also allows service providers to limit web hosting on subscriber lines, orsell it separately; a web server cannot run effectively over ADSL.
What is a Multimedia DBMS?• A multimedia database management system (MM-DBMS) is a framework that manages different types of data potentially represented in a wide diversity of formats on a wide array of media sources.• Like the traditional DBMS, MM-DBMS should address requirements: – Integration • Data items do not need to be duplicated for different programs – Data independence • Separate the database and the management from the application programs – Concurrency control • allows concurrent transactions MM Database 35
What is a Multimedia DBMS?• A multimedia database management system (MM-DBMS) is a framework that manages different types of data potentially represented in a wide diversity of formats on a wide array of media sources.• Like the traditional DBMS, MM-DBMS should address requirements: – Integration • Data items do not need to be duplicated for different programs – Data independence • Separate the database and the management from the application programs – Concurrency control • allows concurrent transactions MM Database 36
Requirements of Multimedia DBMS (cont.)• In addition, an MM-DBMS should: – have the ability to uniformly query data (media data, textual data) represented in different formats. – have the ability to simultaneously query different media sources and conduct classical database operations across them. query support – have the ability to retrieve media objects from a local storage device in a smooth jitter-free (i.e. continuous) manner. storage support – have the ability to take the answer generated by a query and develop a presentation of that answer in terms of audio-visual media. – have the ability to deliver this presentation in a way that satisfies various Quality of Service requirements. presentation and delivery support MM Database 37
Architecture for Distributed Multimedia Server Autonomous Disks 1 2 3 4 5 NConfiguration Manager High Speed Network User Setup 38
Target Features of a Multimedia Server• Support for a variety of multimedia types and formats• Real-time guarantees• Scalable• Reliable 39
Web server A Web server is a program that generates and transmits responses to client requests for Web resources. Handling a client request consists of several key steps: Parsing the request message Checking that the request is authorized Associating the URL in the request with a file name Constructing the response message Transmitting the response message to the requesting client
WEB SERVERS Steps in Handling a Client Request A Web server proceeds through the following steps in handling an HTTP request: Read and parse the HTTP request message for example GET the resource /foo.htm Translate the URL to a file name for example the resource be located in the base directory such as /www, where the URL http://www.bar.com/foo/index.html corresponds to the file of www/foo/index.html Determine whether the request is authorized Generate and transmit the response that includes header to show the status information Web Protocols and Practice
Vector graphics• Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics. "Vector", in this context, implies more than a straight line.• Vector graphics are based on images made up of vectors (also called paths, or strokes) which lead through locations called control points. Each of these points has a definite position on the x and y axes of the work plan.
Introduction to 3d Computer Graphics• 3D computer graphics is the science, study, and method of projecting a mathematical representation of 3D objects onto a 2D image using visual tricks such as perspective and shading to simulate the eyes perception of those objects.
3D computer graphic software• 3Dcomputer graphics software refers to programs used to create 3D computer-generated imagery.• 3D modelers allow users to create and alter models via their 3D mesh. Users can add, subtract, stretch and otherwise change the mesh to their desire. Models can be viewed from a variety of angles, usually simultaneously. Models can be rotated and the view can be zoomed in and out.• 3D modelers can export their models to files, which can then be imported into other applications as long as the metadata is compatible. Many modelers allow importers and exporters to be plugged-in, so they can read and write data in the native formats of other applications.• Most 3D modelers contain a number of related features, such as ray tracers and other rendering alternatives and texture mapping facilities.
What is Animation? The word Animation is generated from word anime which means life. Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement
Beginning of 21st Century• The animators drawings and the backgrounds are either scanned into or drawn directly into a computer system.• Various software programs are used to color the drawings and simulate camera movement and effects• The final animated piece is output to one of several delivery media, including traditional 35mm film and newer media such as digital video
Examples of traditionally animated feature films
(animation techs).1Hand drawn animation• Traditional animation, also referred to as classical animation, cel animation, or hand- drawn animation, is the oldest and historically the most popular form of animation. In a traditionally-animated cartoon, each frame is drawn by hand• Disney used this type of animation, some animators, even those working in the industry today, choose to use the traditional drawn method. Others use computer programmes that simulate the traditional method such as photoshop
2.Stop Motion AnimationStop-motion animation, is the term used to describe animation created by physically manipulating real-world objects and photographing them one frame of film at a time to create the illusion of movement.There are many different types of stop-motion animation, usually named after the type of media used to create the animation, these include:• Cutout animation• Claymation animation• Model animation (like the classic King-Kong)• Object animation• Puppet animation
3.Cutout Animation Cutout animation is a unique technique for producing animations using flat characters, props and backgrounds cut from materials such as paper, card, stiff fabric or even photographs. The worlds earliest known animated feature films were cutout animations (made in Argentina by Quirino Cristiani as early as 1917) Angela Anaconda is a contemporary example of the use of cutoutanimation. The programme combines black-and-white photographs with cutout-style CGI animation. http://www.youtube.com/watch?v=utgXR6k-P1s
4.Clay animation • In clay animation, which is one of the many forms of stop motion animation, each object is sculpted in clay or a similarly pliable material such as Plasticine, usually around a wire skeleton called an armature.
5.Computer animation• Computer animation encompasses a variety of techniques, the unifying idea being that the animation is created digitally on a computer.• The term covers 2D animation using Flash to the CGi techniques used in Pixar’s many successful films. http://www.youtube.com/watch?v=D5YmIS5 7J9E
6.Drawn on film animation• Drawn on film animation (also known as "direct animation", or "animation without camera") is an animation technique where footage is produced by creating the images directly on film stock, as opposed to any other form of animation where the images or objects are photographed frame by frame with an animation camera• There are two basic methods to produce animation directly on film. One starts with blank film stock, the other one with black (already developed) film. On blank film the artist can draw, paint, stamp, or even glue objects. Black film (or any footage) can be scratched, etched, sanded, or punched. Any tool the artist finds useful may be used for this, and all techniques can be combined endlessly. The frame borders may be observed or completely ignored, found footage may be included, any existing image might be distorted by mechanical or chemical means.
Shading• Shading refers to depicting depth perception in 3D models or illustrations by varying levels of darkness.• Anti-aliasing-it is a process used to remove jagged edges in computer graphics. The blurring of hard edges to create the appearance of smoothness. Most commonly used with respect to graphics, especially text.
Morphing• Morphing is a special effect in motion pictures and animations that changes (or morphs) one image into another through a seamless transition.• Most often it is used to depict one person turning into another through technological means or as part of a fantasy or surreal sequence.• Traditionally such a depiction would be achieved through cross-fading techniques on film. Since the early 1990s, this has been replaced by computer software to create more realistic transitions.
video on demand• Video on Demand (VOD) or Audio and Video on Demand (AVOD) are systems which allow users to select and watch/listen to video oraudio content on demand.• IPTV technology is often used to bring video on demand to televisions and personal computers. Catch up TVis a form of video on demand.• Some airlines offer AVOD as in-flight entertainment to passengers through individually controlled video screens embedded in seatbacks or armrests or offered via portable media players.
(Sec-B) Image Compression & StandardsMaking still images-Still images are visual representations that do not move.• Still images, however, allow the content creator to convey information which can be more freely interpreted by the user.• Still images may be the most important element of a multimedia project.• The type of still images created depends on the display resolution, and hardware and software capabilities.
Types of still imagesStill images are generated in two ways: – Bitmaps. – Vector-drawn graphics• Bitmaps-It is derived from the words ‘bit’, which means the simplest element in which only two digits are used, and ‘map’, which is a two-dimensional matrix of these bits.• A bitmap is a data matrix describing the individual dots of an image.Bitmaps are an image format suited for creation of: – Photo-realistic images. – Complex drawings. – Images that require fine detail.
BitmapsAvailable binary Combinations for Describing a Color
BitmapsBitmaps can be inserted by: – Using clip art galleries. – Using bitmap software. – Capturing and editing images. – Scanning images.The industry standard for bitmap painting and editing programs are: • Adobes Photoshop and Illustrator. • Macromedias Fireworks. • Corels Painter. • CorelDraw. • Quark Express.
Using Clip Art Galleries• A clip art gallery is an assortment of graphics, photographs, sound, and video.• Clip arts are a popular alternative for users who do not want to create their own images.• Clip arts are available on CD-ROMs and on the Internet.
Capturing and Editing Images -impImage editing programs enable the user to: – Enhance and make composite images. – Alter and distort images. – Add and delete elements. – Morph (manipulate still images to create animated transformations). Scanning images-Users can scan images from conventional sources and make necessary alterations and manipulations.
Vector-Drawn Graphics• Applications of vector-drawn images.• How vector-drawn images work?• Vector-drawn images v/s bitmaps.Applications of Vector-Drawn Images- – Computer-aided design (CAD) programs. – Graphic artists designing for the print media. – 3-D animation programs. – Applications requiring drawing of graphic shapes.
How Vector-Drawn Images Work• A vector is a line that is described by the location of its two endpoints.• Vector drawing makes use of Cartesian co- ordinates.• Cartesian coordinates are numbers that describe a point in two or three-dimensional space as the intersection of X, Y, and Z axis.
Vector-Drawn Images v/s Bitmaps• Vector images use less memory space and have a smaller file size as compared to bitmaps.• For the Web, pages that use vector graphics in plug-ins download faster, and when used for animation, draw faster than bitmaps.• Vector images cannot be used for photorealistic images.• Vector images require a plug-in for Web-based display.• Bitmaps are not easily scalable and resizable.• Bitmaps can be converted to vector images using autotracing.
Computer &Color ModelsModels used to specify color in computer terms are: – RGB model - A 24-bit methodology where color is specified in terms of red, green, and blue values ranging from 0 to 255. – HSB and HSL models – Color is specified as an angle from 0 to 360 degrees on a color wheel. – Other models include CMYK, CIE, YIQ, YUV, and YCC.
Color Palettes• Palettes are mathematical tables that define the color of pixels displayed on the screen.• Palettes are called ‘color lookup tables’ or CLUTs on Macintosh.• The most common palettes are 1, 4, 8, 16, and 24-bit deep.Dithering: – Dithering is a process whereby the color value of each pixel is changed to the closest matching color value in the target palette. – This is done using a mathematical algorithm.
Vector drawing• Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics. "Vector", in this context, implies more than a straight line.
3D drawing• whenever we look a things they are in three dimensions we see thgs in length height and width. Drawings that are created to represent the three dimensions is called a 3-D drawing• A 3 dementional shape, object or thing you draw upon a peice of paper that shows you the perspective and shading used to help make the drawing more realistic.
3D Rendering• The process of taking the mathematical model of the world and producing the output image.• The core of the rendering process involves projecting the 3D models onto a 2D image plane.
Types of Rendering Algorithms• Two general approaches: – Pixel-oriented rendering: • Ray tracers – Polygon-oriented rendering: • Scan-line renderers
1.Ray tracers• Operates by tracing theoretical light rays as they intersect objects in the scene and the projection plane.
2.Scan-line renderers– Operate on an object-by-object basis, directly drawing each polygon to the screen.– Requires all objects – including those modeled with continuous curvature – to be tessellated into polygons.– Polygons are eventually tessellated into pixels.
JPEG Introduction - The background• JPEG stands for Joint Photographic Expert Group• A standard image compression method is needed to enable interoperability of equipment from different manufacturer• It is the first international digital image compression standard for continuous-tone images (grayscale or color)• The history of JPEG – the selection process
JPEG objective-• “very good” or “excellent” compression rate, reconstructed image quality, transmission rate• be applicable to practically any kind of continuous-tone digital source image• good complexity• have the following modes of operations: – sequential encoding – progressive encoding – lossless encoding – hierarchical encoding
JPEG Overview Source encoder compressed Encoder descriptors symbols entropyimage data statistical image data model encoder model model entropy tables coding tables The basic parts of an JPEG encoder
JPEG • Architecture of standard • Forward transform • Quantization • Entropy coding – DC coefficient – AC coefficientsSource Forward Entropy Compressedimage data transform Quantization encoding image data
JPEG Source Entropy Compress image Forward Quantizati encoding ed image data transform on data• Forward transform 1. Level shifted 2 p 1 2. Divided into blocks of 8*8 pixels 3. Forward DCT: 1 2j 1i cos i 0, j 0 ,1,..., N 1 N 2N C i, j 2 2j 1i cos i 0 ,1,..., N 1, j 0 ,1,..., N 1 N 2N
JPEG Source Forwar Quantiza Entrop Compre image d tion y ssed data transfor encodin image m g data• Entropy encoding • DC coefficient and AC coefficients are coded differently • DC coefficient – Encode the difference – Huffman code unmanageable Category Possible values 0 0 1 -1 1 2 -3 -2 23 3 -7 -6 -5 -4 4567 – First bits to define the category and other bits to define the element in the category
JPEG• AC coefficients Defined by a certain number of terms: » Category C that a non zero label falls in » Z: number of zero since the last non zero label – Z/C points to a specific code – Follows by bits to define the element in the category – +1 code » EOB stands for End Of Block: A code after the last non zero value
JPEG• More accurate image – Increase the bit rate – Decrease quantization table elements• Less accurate image – Decrease the bit rate – Increase quantization table elements• Problem:Low rate image: « blockiness »
Lossless Predictive Coding• Prediction up [n] is calculated for x[n] from previous samples• e[n] is prediction error, with greatly reduced statistical dependencies between adjacent samples• Entropy coder may assume i.i.d. prediction error e[n]• Receiver can reconstruct x[n] without loss for amplitude-discrete signals• Much simpler than context-adaptive coder
Graphics interchange format• The Graphics Interchange Format (GIF; /ˈ dʒɪf/ or /ˈ ɡɪf/) is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability.• The format supports up to 8 bits per pixel thus allowing a single image to reference a palette of up to 256 distinct colors. The colors are chosen from the 24-bit RGB color space.• It also supports animationsand allows a separate palette of 256 colors for each frame. The color limitation makes the GIF format unsuitable for reproducing color photographs and other images with continuous color, but it is well-suited for simpler images such as graphics or logos with solid areas of color.• GIF images are compressed using the Lempel-Ziv- Welch (LZW) lossless data compression technique to reduce the file size without degrading the visual quality
Usage of GIFs• GIFs are suitable for sharp-edged line art (such as logos) with a limited number of colors. This takes advantage of the formats lossless compression, which favors flat areas of uniform color with well defined edges.• GIFs can be used to store low-color sprite data for games.• GIFs can be used for small animations and low-resolution film clips.• In view of the general limitation on the GIF image palette to 256 colors, it is not usually used as a format for digital photography. Digital photographers use image file formats capable of reproducing a greater range of colors, such as TIFF, RAW or JPEG
TIFF• TIFF (originally standing for Tagged Image File Format) is a file format for storing images, popular among graphic artists, the publishing industry,]and both amateur and professional photographers in general.• As of 2009, it is under the control of Adobe Systems. Originally created by the companyAldus for use with "desktop publishing", the TIFF format is widely supported by image-manipulation applications, by publishing and page layout applications, by scanning, faxing, word processing, optical character recognition and other applications.• Adobe Systems, which acquired Aldus, now holds the copyright to the TIFF specification.
BMP• The BMP file format, also known as bitmap image file or device independent bitmap (DIB) file format or simply a bitmap, is a raster graphicsimage file format used to store bitmap digital images, independently of the display device (such as a graphics adapter), especially on Microsoft Windows and OS/2 operating systems.• The BMP file format is capable of storing 2D digital images of arbitrary width, height, and resolution, both monochrome and color, in various color depths, and optionally with data compression, alpha channels, and color profiles.
PNG• Portable Network Graphics (PNG pron.: /ˈ  PING) is pɪŋ/ a bitmapped image format that employs lossless data compression.• PNG was created to improve upon and replace GIF (Graphics Interchange Format) as an image-file format not requiring a patent license.• PNG supports palette-based images (with palettes of 24- bit RGB or 32-bit RGBA colors), grayscale images (with or without alpha channel), and full-color non-palette-based RGB[A] images (with or without alpha channel). PNG was designed for transferring images on the Internet, not for professional-quality print graphics, and therefore does not support non-RGB color spaces