Image and Video •formates

Presented By:• Prerak

•Video Basics

•Codec• • –A codec is an algorithm, which can be

thought of as a list of instructions that identifies the method used to compress data into fewer bytes.–By following these instructions, applications

such as encoders and players can reliably compress and decompress data. In the case of digital media content, codecs are used to decrease the content's file size and bit rate (the amount of data per second that is required to render audio and video content). –With smaller file sizes and lower bit rates,

digital media content can be stored and streamed over a network more quickly and easily.

•Introduction to Video,Persistence of Vision

The persistence of vision theory states that the human eye holds a still image for a fraction of a second, remaining on the retina long enough to blend with the next image.

Film displays 24 still images each second (frames per second or fps).

•How video compression works?•Video compression works on square shaped

group of neighboring pixels called macroblocks.

•The group of pixels in different frames are compared and only difference between them is sent so redundancy is reduced and size is also reduced.

•So if there is much more motion in the movie then compression doesn’t work efficiently and size is not much reduced. Ex: Fire scenes, explosions

•So variable bitrate is increased to maintain the quality.

•MPEG•What is MPEG?

• MPEG stands for the Motion Picture Experts Group,which is part of the International Organization for Standardization(ISO) and International Electrotechnical Commission(IEC).

• However, MPEG is charged with creating and• publishing standards for various

technology.

•Video compression formates•ISO/IEC:•MPEG-1  MPEG-2  MPEG-4 ASP 

MPEG-4/AVC

•ITU-T:•H.261  H.262  H.263  H.264

•Others:•AVS  Bink  Dirac  Indeo  MJPEG 

RealVideo · Theora  VC-1  VP6  VP7  WMV

•

•MPEG-1

•MPEG-1 video is used by the Video CD (VCD) format and less commonly by the DVD-Video format.

•The quality at standard VCD resolution and bitrate is near the quality and performance of a VHS tape.

•MPEG-1, Audio Layer 3 is the popular audio format known as MP3.

•MPEG-2

•MPEG-2 is the core of most digital television and DVD formats.

•It is widely used around the world to specify the format of the digital television signals that are broadcast by terrestrial (over-the-air), cable, and direct broadcast satellite TV systems.

•It also specifies the format of movies and other programs that are distributed on DVD and similar disks.

•The standard allows text and other data, e.g., a program guide for TV viewers

•MPEG-4•MPEG-4 is the new worldwide standard for

interactive multimedia creation, delivery, and playback for the Internet.

•What MPEG-1 and its delivery of full-motion , full-screen

•video meant to the CD-ROM industry

•MPEG-2 meant to the development of DVD,

•MPEG-4 will mean to the Internet.

•MPEG-4•

•MPEG-4 AVC , H.264 : • Apple QuickTime , IPOD , PSP

• MPEG-4 Part 2 , MPEG-4 ASP:• DivX , Xvid

•WMV

•WMV is a generic name for the set of video codec technologies developed by Microsoft. It is part of the Microsoft Windows Media framework.

•Video File ( Container_format )

•MPEG-4 AVC ???

•H.264 ???

•DivX ????

• Different Container

• Standard owner

• Subtitles • Video formats supported • Audio formats supported

• 3GP , 3G2

• 3GPP

• 3GPP Timed Text

• MPEG-4, H.263 and H.264/MPEG-4 AVC

• AMR-NB/WB, AMR-WB+ and (HE)-AAC

• ASF • Microsoft

• Yes • Almost anything through VFW or DMO, H.264/AVC is problematic

• Almost anything through ACM or DMO, Vorbis is problematic

• AVI • Microsoft

• Yes, via third party modifications

• Almost anything through VFW, H.264/AVC is problematic due to the limited b-frame support[4]

• Almost anything through ACM, Vorbis is problematic [5]

• DIVX • DivX • Yes • DivX video encoded to meet DivX Profiles

• MP3, PCM, AC-3

• EVO • MPEG

•  ? • MPEG-2 Part 2, H.264/MPEG-4 AVC, VC-1

• AC-3, E-AC-3, Dolby TrueHD, Linear PCM, DTS, DTS-HD, MPEG-2 Part 3

• Different Container

• Standard owner

• Subtitles • Video formats supported

• Audio formats supported

• MKV , MKA

• public domain • Yes, anything, including embedded fonts

• Yes, anything • Yes, anything

• MCF • BSD-style license for specs, GNU for tools

• ? • Anything • Anything

• MPEG • MPEG • Only in VOB files on DVDs

• MPEG-1, MPEG-2

• MPEG-1 Layers I, II, III (mp3), AC-3, LPCM, DTS

• MPG • MPEG • possible via ETSI EN 300 743

• MPEG-1, MPEG-2, MPEG-4 ASP, H.264/MPEG-4 AVC

• MPEG-1 Layers I, II, III (mp3), AC-3, LPCM, DTS, AAC

• MOV • Apple • Yes • Anything through QuickTime codec manager

• Anything through Sound Manager or CoreAudio

• MP4 • MPEG • ttxt, VobSubs with privat objectTypeIndication not usable with the sceneDescription (started by Nero), BIFS

• MPEG-1, MPEG-2, H.263, MPEG-4 ASP, H.264/MPEG-4 AVC

• MPEG-1 Layers I, II, III (MP3), MPEG-2/4 (HE)-AAC, Vorbis (with privat objectTypeIndication), Apple Lossless

• Different Container

• Standard owner

• Subtitles • Video formats supported

• Audio formats supported

• NUT • NUT Project/GPL

• Yes • Virtually anything • Virtually anything

• OGG/OGM

• Xiph.org • Ogg Writ, SRT and MicroDVD with OGMtools.

• Theora, almost anything through VFW, H.264/AVC doesn't work

• Vorbis, almost anything through ACM

• RMVB

• RealNetworks

• Yes • RealVideo 8, 9, 10 • (HE)-AAC, Cook Codec, Vorbis, RealAudio Lossless

• VOB • MPEG • VobSub • MPEG-2 Part 2 • AC-3, Linear PCM, DTS, MPEG-2 Part 3, MPEG-1 Layer II

•Image Basics

•A digital image is a numeric representation of a two dimensional image.

•Most software developers created a new custom file format for each application they develop.

•Using Standardized file formats increases the ease with which images can be exchanged and be readable by other software .

•1-Tagged Image Format File (TIFF):•

A TIFF file can contain a number of images with different properties.––A TIFF specification provide a range of different compression methods;( LZW, ZIP, CCITT & JPEG) and color spaces which make it easy to store a number of variations of an image in different sizes & representations together in a single TIFF file.––The flexibility of a TIFF has made it

universal exchange format used in archiving documents , scientific applications, digital photography and video production.

•Merits of TIFF format:•

The great advantage of saving files in the same TIFF format is that no information is lost.

Useful for transporting image files from one application to another or from one computer to another as they are designed to be independent of any particular hardware or software.

– The strength of TIFF format lies in its architecture , which enables new image types & information blocks to be created by defining new “tags” .

•Demerits of TIFF format:•

TIFF files encounter errors when loading. In flexibility also lies the weakness of this format where proprietary tags are not always supported.

The drawback of TIFF files is that the file size is large. They take up a lot of space when stored and take a long time to open in an application.

– Difficult to store. They are not useful as embedded image files in a webpage as they take much too long to download.

•2- Graphics Interchange Format (GIF) :••Widely popular format; due to its early support for indexed color at multiple bit depths, LZW compression, interlaced image loading.

•• Designed for color & grayscale images

with maximum 8bit depth (i.e. doesn’t support true color images). GIF files are designed to efficiently encode flat images consisting of large areas of the same color.––Supports color palletes in the range of (2-

256); enabling pixels to be encoded using fewer bits.

•Merits of GIF format:•• The limited color range has the advantage

that GIF files will be smaller in size.•• Easy to store and display: When

saving an image as GIF, you can specify how the image appears as it is downloaded. Select “Interlaced” to display the image gradually in increasing detail as it is downloaded.

•• GIF format has the ability to encode simple animations by storing a number of images in a single file for later sequential display. Also  can be made into a transparent image.

•Demerits of GIF format:  The limitation of an 8-bit palette, or 256 colors makes the GIF format suitable for storing graphics with relatively few colors such as simple diagrams, shapes, logos & cartoon style images and ineffective for detailed images or dithered images.

• Loss of color variation. GIF is not suitable for subtle color variations retained in your image. Gif formats are very useful for storing grey scale images which are limited to 256 tones of grey, so that no information is lost .

•3-Portable Network Graphics (PNG):•

A universal image format designed especially for the use of the internet. PNG format was designed to be an alternative to the GIF format .••PNG files support 3 types of images:•1) true color (with up to 3*16 bits/pixel)•2) grayscale (with up to 16bit/pixel)•3) indexed (with up to 256 colors).••PNG includes an alpha channel for

transparency with a maximum width of 16bit.

•Merits of PNG format:•

Unlike GIF, the PNG format is able to retain full 16,000,000 colors. Still the format support one image per file but it allows images of up to 2^30 * 2^30 pixels.

The PNG format  uses a lossless compression method .

–

•Demerits of PNG format: •

• Relative large file size ensures PNG format may be less suitable for Web or other online service.

•4-Joint Photographic Experts Group (JPEG):

It’s a standard defines a compression method used to display continuous tone images (such as photographs) with a goal of achieving an average data reduction of 1:16.

The level of JPEG compression will determine how much information is lost (this can be set in most programs that offer jpeg compression).

• Jpeg files can be saved with the following options: "standard", "baseline optimized" and "progressive".

•Algorithm Core of RGB image:••1) color conversion & down sampling:

color transformation from RGB into the Y Cb Cr space is used to separate the actual color components from the brightness Y component.

•Algorithm Core of RGB image:2) Cosine transform & quantization in frequency space: The image is divided up to a regular grid of 8 blocks. The frequency spectrum is computed for each independent block using the discrete cosine transformation. Next the spectral coefficients of each block is quantized using quantization table; size of this table determines the compression ratio.

•3) Lossless compression: The quantized spectral components data stream is again compressed using lossless method (arithmetic or Huffman) in order to remove the last redundancy in the data stream.

•Merits and Demerits of JPEG formats:• Merits:

Retains up to 16,000,000 colors. The ability to compress more or less to find a compromise between file size and image quality.

Demerits:

Loses information on pixel frequency values because they may be averaged to the values of those pixels in its immediately surroundings.

File size larger than gif because of color information.

• JPEG file formats:•

JFIF: What is normally referred to as JPEG is an instance of “JPEG File Interchange Format”(JFIF) .It specifies a file format based on the JPEG standard by defining the remaining necessary elements of the file format.

EXIF: The exchangeable image file format, Is a variant of (JFIF) designed for storing image data originating on digital cameras. It is the practically used file format by all manufacturers as the standard format for storing digital images on memory cards.

•JPEG-2000: was designed to overcome some of the weaknesses of traditional JPEG codec. Higher compression ratios achieved here (up to 0.25bit/pixel), the use of larger 64*64 blocks & the replacement of the cosine transform by Wavelet transform.

•Example• Origin

al• 1.5

MB

• Lossy Compressio

n• 92 KB

•File Type Comparison

• Overview

• Extension • Colour • Compression • Common Uses

• JPG, JPEG • 24-bit • Lossy • Photos, web pics

• GIF • 8-bit • Lossless • Web graphics – buttons, icons, etc

• PNG • up to 24-bit

• Lossless • Web – replacement for GIF

• TIF, TIFF • 24-bit • Lossless Professional• Photos etc

•Thank you...