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GIF (Graphics Interchange Format) is a bitmap image format that is widely used on the World Wide Web, both for still images and for animations. For the use of the term raster in radio regulation, see frequency raster. ...
See also Category:Graphics file formats Here is a summary of the most common graphics file formats: Some file formats, e. ...
Graphic representation of the world wide web around Wikipedia The World Wide Web (WWW, or simply Web) is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URI). ...
Image of the Wikimedia Commons logo. ...
Animation refers to the technique in which each frame of a film or movie is produced individually, whether generated as a computer graphic, or by photographing a drawn image, or by repeatedly making small changes to a model (see claymation and stop motion), and then photographing the result. ...
The format was introduced in 1987 by CompuServe in order to provide a color image format for their file downloading areas, replacing their earlier RLE format which was black and white only. GIF became popular because it used LZW data compression, which was more efficient than the run-length encoding that formats such as PCX and MacPaint used, and fairly large images could therefore be downloaded in a reasonable amount of time, even with very slow modems. 1987 is a common year starting on Thursday of the Gregorian calendar. ...
CompuServe was a major online service during the 1980s and 1990s before it was sidelined by the rise of GUI-based services such as America Online. ...
LZW (Lempel-Ziv-Welch) is a lossless data compression algorithm. ...
In computer science, data compression or source coding is the process of encoding information using fewer bits, or information units, thanks to specific encoding schemes. ...
Run-length encoding (RLE) is a very simple form of data compression in which runs of data (that is, sequences in which the same data value occurs in many consecutive data elements) are stored as a single data value and count, rather than as the original run. ...
PCX is an image file format that uses a simple form of run-length encoding (a type of lossless compression algorithm). ...
MacPaint is a bitmap-based image editing computer program that was produced by Apple Computer for bundling with their Macintosh personal computer. ...
A modem (a portmanteau word constructed from modulator and demodulator) is a device that modulates an analog carrier signal (sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information. ...
The optional interlacing feature, which stored image scanlines out of order in such a fashion that even a partially downloaded image was somewhat recognizable, also helped GIF's popularity, as a user could abort the download if it was not what was required.
GIF is widely believed to be limited to 256 colors though this is not strictly true.
English speakers often pronounce "GIF" with either an affricate as in "giraffe" /dʒɪf/ or a plosive as in "gift" /gɪf/. The format's creators are quoted as using an affricate to pronounce the acronym. There is plenty of evidence to suggest this, much of which can be found here: [1] (http://www.olsenhome.com/gif/). However, many people use the plosive pronounciation in daily conversation. The affricate was used as the developers had a sense of humour "Choosy Developers Choose GIF", making a play on a then famous commercial for peanut butter. Outside of the English language there are a number of further variants.
History
The original version of GIF was 87a. In 1989, CompuServe devised an enhanced version, called 89a [2] (http://www.w3.org/Graphics/GIF/spec-gif89a.txt), that added support for multiple images in a stream, interlacing and storage of application-specific metadata. The two versions can be distinguished by looking at the first six bytes of the file, which, when interpreted as ASCII, read "GIF87a" and "GIF89a", respectively. This article refers to the unit of binary information. ...
There are 95 printable ASCII characters, numbered 32 to 126. ...
When the World Wide Web gained popularity, GIF became one of the two image formats commonly used on Web sites, the other being JPEG. Most Internet browsers at this time did not support any other image formats, not even uncompressed Windows bitmap files, to discourage web designers from using files larger than necessary. A photo of a flower compressed with successively higher compression ratios from left to right. ...
.BMP or . ...
The GIF89a feature of storing multiple images in one file, accompanied by control data, is used extensively on the web to produce simple animations. Computer animation is the art of creating moving images via the use of computers. ...
Unisys and LZW patent enforcement The LZW compression algorithm on which GIF is based, was covered by U.S. Patent 4,558,302 (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,558,302.WKU.&OS=PN/4,558,302&RS=PN/4,558,302) owned by Unisys. When Compuserve first developed the GIF they did not know that LZW was covered by a patent. Unisys Corporation (NYSE: UIS) is a provider of information technology services and solutions with operations across the world. ...
A patent is a set of exclusive rights granted by a government to an inventor or applicant for a limited amount of time (normally maximum 20 years from the filing date, depending on extension). ...
Before 1994, Unisys was not aware that GIF used LZW. In December 1994, after Unisys discovered that GIF used the LZW, they announced that they would be seeking royalties on that patent; all commercial programs capable of producing GIF files would be required to pay a license fee to Unisys. 1994 was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ...
By this time, GIF was in such widespread use that most companies producing these programs had little choice but to pay. The desire for a format with fewer legal restrictions (as well as fewer technical restrictions such as the number of colours) led to the development of the PNG format, which has become the third most common image format on the Web. PNG (Portable Network Graphics), sometimes pronounced as ping, is a relatively new bitmap image format that is becoming popular on the World Wide Web and elsewhere. ...
In late August 1999, Unisys terminated its royalty-free LZW technology licenses for free software and non-commercial proprietary software and even for individual users of unlicensed programs, prompting the League for Programming Freedom to launch the Burn All GIFs campaign to inform the public of the alternatives. League for Programming Freedom (LPF) was founded in 1989 by Richard Stallman to unite free software developers as well as developers of proprietary software to fight against software patents and the extension of the scope of copyright. ...
On June 20, 2003, the United States patent on the LZW algorithm expired [3] (http://www.unisys.com/about__unisys/lzw), which means that Unisys and Compuserve can no longer collect royalties for use of the GIF format in that country. Those bothered with the patent enforcement dubbed this day GIF Liberation Day. The equivalent patents in Europe and Japan expired on June 18 and June 20, 2004 respectively, with the Canada patent following on July 7. June 20 is the 171st day of the year (172nd in leap years) in the Gregorian Calendar, with 194 days remaining. ...
June 18 is the 169th day of the year in the Gregorian Calendar (170th in leap years), with 196 days remaining. ...
June 20 is the 171st day of the year (172nd in leap years) in the Gregorian Calendar, with 194 days remaining. ...
July 7 is the 188th day of the year (189th in leap years) in the Gregorian Calendar, with 177 days remaining. ...
IBM has also patented the LZW algorithm, but has never enforced this patent. According to the Free Software Foundation that patent will expire on August 11, 2006 in the United States. Free Software Foundation (FSF) is a non-profit organisation founded in 1985 by Richard Stallman to support the free software movement (free as in freedom), and in particular the GNU project. ...
August 11 is the 223rd day of the year (224th in leap years) in the Gregorian Calendar. ...
2006 is a common year starting on Sunday of the Gregorian calendar. ...
Usage Even with the general adoption of broadband, the size of downloads continues to be a critical issue on the world wide web. Large web pages have a negative effect on user experience by being slow to render. Large web pages are also more expensive for their owners who pay by the megabyte once traffic has passed a certain level. Therefore GIF's compression makes it desirable as an image format for use on webpages. Mashimaro is a Korean fictional character. ...
Broadband in general refers to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission. ...
Graphic representation of the world wide web around Wikipedia The World Wide Web (WWW, or simply Web) is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URI). ...
This article is about a unit of data measurement. ...
GIF is the only widely used image format to support animation. It is frequently used to make small animations and short, low-resolution films for web pages.
Most web page logos and design element images are GIF or PNG because those are designed to successfully compress images that contain large blocks of the same color or of repeating patterns; JPEG cannot compress areas of flat, clean color well. A photo of a flower compressed with successively higher compression ratios from left to right. ...
JPEG is preferred for digital photographs because it allows images to contain more than 16 million different colors (GIF gives a choice of only 256 of those colors per image) and it compresses photographs better. Uncompressed bitmap formats like Windows bitmap are sometimes preferred for images in computer software when speed is more important than reduced file size, because uncompressed bitmaps can be displayed more quickly. The Nikon Coolpix 950 Casio Exilim Digital photography, as opposed to film photography, uses an electronic sensor to record the image as a piece of electronic data rather than as chemical changes on film. ...
.BMP or . ...
Computer software (or simply software) refers to one or more computer programs held in the storage of a computer for some purpose. ...
Color GIF is palette based: although any color can be one of millions of shades, the maximum number of colours available for each frame is 256, which are stored in a "palette", a table which associates each colour number with an actual colour value. The limitation to 256 colours seemed reasonable at the time of GIF's creation because few people had the hardware to display more. Simple graphics line drawings, cartoons, and grayscale photographs typically need less than 256 colors. Optionally, one of the colors in the palette can be set as transparent, hence achieving simple binary transpareny. For alternative meanings, see color (disambiguation). ...
There exist ways to dither color photographs by alternating pixels of similar colous to approximate an in-between colour, but this transformation inevitably loses some detail, and the algorithms to select colours and to perform the dithering vary widely in output quality, giving dithering a possibly unwarranted bad reputation. Additionally, dithering significantly reduces the image's compressibility and thus works contrary to GIF's main purpose. This article or section should be merged with Dither An illustration of dithering. ...
Flowcharts are often used to represent algorithms. ...
GIF89a was designed based on the principle of rendering images to a logical screen. Each image could optionally have its own pallette and it was up to the tool producing the gif whether to put any delay between them. This feature is what is used to create animated gifs but it can also be used to losslessly store a 24 bit rgb (truecolor) image by splitting it up into peices small enough to be encoded into a 256 color pallette and setting up the gif to render theese with no delay on the logical screen. Unfortunately most web browsers seem to assume that this multi image feature will only be used for animation and insert a minium delay between images. There will be some filesize bloat from doing this especially if the encoder doesn't support lzw for patent reasons. There are very few tools around that can easilly produce truecolor gifs and it is rarely an appropriate format unless there is absoloutely no other option. (demo (http://phil.ipal.org/tc.html))
Alternatives The PNG format was specifically designed to replace GIF for use as a single-image web format. PNG offers better compression and more features than GIF. The format is rapidly replacing GIF for still images, mostly on web sites of computer enthusiasts protesting Unisys's license policies and on some cartoon sites that take advantage of PNG's tighter compression to save on Internet bandwidth charges. PNG (Portable Network Graphics), sometimes pronounced as ping, is a relatively new bitmap image format that is becoming popular on the World Wide Web and elsewhere. ...
A cartoon is a form of art with diverse origins and even more diverse modern meanings. ...
Analog Bandwidth is the width, usually measured in hertz, of a frequency band f2 − f1. ...
All the features of GIF except animation are supported by PNG. As new web browsers support PNG, most GIF images could be replaced by PNG images. The most recent versions of Internet Explorer, however, do not support PNG's 8-bit alpha transparency, a feature absent from GIF images which only provides 1-bit transparency, i.e., pixels are either fully transparent or fully opaque. This is not a problem with many other web browsers. Version 7 of the browser, however, will finally support this missing feature [4] (http://blogs.msdn.com/ie/archive/2005/04/22/410963.aspx). A web browser is a software package that enables a user to display and interact with documents hosted by web servers. ...
Internet Explorer, abbreviated IE or MSIE is a web browser from Microsoft currently sold as part of Microsoft Windows. ...
The mistaken belief that PNG files are larger than GIF for the same images can generally be traced back to one of two things:
- People making the unfair comparision of the file size of 8 bit GIF with 24 bit PNG.
- The poor PNG support in older versions of Adobe Photoshop.
MNG, the animation-supporting relative of PNG, reached version 1.0 in 2001, but few applications support it. It has therefore had little impact on the use of GIFs for animation. Today animations may be the only field where GIF is needed, because of the lack of web browser support for MNG. Adobe Photoshop is a bitmap graphics editor (with some text and vector graphics capabilities) developed and published by Adobe Systems. ...
MNG (pronounced ming) is a public file format for animated images. ...
In 2004, a proposed extension to the PNG format, called APNG was suggested. It would add the ability to animate PNG files, while retaining backwards compatibility in decoders which cannot understand the animation chunk. Such decoders would simply display it as though it were a single image PNG file. The APNG (Animated Portable Network Graphics) file format is a proposed extension to the portable network graphics (PNG) specification that would allow for animated PNG files that work in a similar fashion to animated graphics interchange format (GIF) files, while retaining the backward compatibility with non-animated PNG files. ...
Miscellaneous The MIME media type for GIF is image/gif (defined in RFC 1341). A mime is the representation of action, character or mood using only gestures and movements rather than words, or the actor in such a performance, specifically a mimic or pantomimist. ...
Alternate meaning: Wikipedia:Requests for comment A Request for Comments (RFC) document is one of a series of numbered Internet informational documents and standards very widely followed by both commercial software and freeware in the Internet and Unix communities. ...
See also Software patents are a type of intellectual property and one of many legal aspects of computing. ...
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