GIF - Revision history

Jsummers at 13:58, 27 March 2025

2025-03-27T13:58:03Z

2024-04-23T19:05:31Z

Category:Animation

2023-12-28T04:21:29Z

‎Sample files

2023-10-12T11:28:51Z

‎Software: Reggae

2023-08-28T15:56:50Z

‎Related formats

2023-03-20T16:51:29Z

‎Format details

2022-12-27T15:38:30Z

‎External links

2022-09-15T15:03:20Z

Minor rearranging

2022-09-09T19:51:49Z

‎Format details: Added non-application extensions

2022-09-09T19:48:15Z

‎Format details: Cleanup, rewriting

@@ Line 136: / Line 136: @@
 |<code>"PIANYGIF"</code>
 |Apparently associated with Ulead GIF Animator.
 |}

@@ Line 225: / Line 225: @@
 <references/>
-[[Category:Video]]
+[[Category:Animation]]
 [[Category:Netscape]]

@@ Line 171: / Line 171: @@
 * [http://gifcities.org/ GifCities: GeoCities animated GIF archive]
 * http://whatis.rest7.com/how-to-open-gif-file
-* https://telparia.com/fileFormatSamples/image/gif/
+* {{DexvertSamples|image/gif}}
 == Metaformat files ==

@@ Line 190: / Line 190: @@
 * [https://ezgif.com/maker Online animated GIF maker]
 * {{CdTextfiles|simtel/stmsdos9709/disk1/DISC1/GRAPHICS/2SHOW204.ZIP|CompuShow 2000! v2.04a}} - DOS program, descendant of one of the first GIF viewers
 == File conversions ==

@@ Line 147: / Line 147: @@
 * [[GIFEXE]]
 * [[Gifpress]]
 * [[GIFV]]
 * [[Jeff's Image Format]]

@@ Line 132: / Line 132: @@
 |<code>"GIFLITE&nbsp;&nbsp;&nbsp;&nbsp;"</code>
 |GIFLITE[https://archive.org/details/msdos_festival_GIFLT210] header
 |}

@@ Line 214: / Line 214: @@
 * [http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html High quality GIF with FFmpeg]
 * [http://theknow.denverpost.com/2017/05/11/gif-exhibit-boulder-museum-of-contemporary-art-ello-2017/143862/ Are GIFs fine art? Ello and the Boulder Museum of Contemporary Art think so]
 == References ==

@@ Line 65: / Line 65: @@
 [[Jeff's Image Format]] is a GIF-like format identified by '''JIF99a'''. The [[file command]]'s database suggests that GIF-like formats identified by '''GIF94z''' ("ZIF") and '''FGF95a''' ("FGF") were experimented with.
-== Color format ==
+== Format details ==
 GIF images are always paletted. The number of colors in a palette can be any power of 2 from 2 to 256.
 If a GIF file contains multiple images, each may have its own palette. This makes it possible for animated GIFs to construct frames that exceed the usual limit of 256 colors<ref>[http://phil.ipal.org/tc.html True-Color GIF Example]</ref>. This technique is inefficient, and may result in very large files.
 === Extensions ===

@@ Line 82: / Line 82: @@
 {| class="wikitable"
 ! Type !! App ID & auth code !! Description
 |-
 |<code>0xff</code>

@@ Line 71: / Line 71: @@
 == Format details ==
-A GIF file has a header (consisting of a signature, a ''screen descriptor'', and optionally a ''global color table''), followed by a sequence of tagged blocks of various types.
+A GIF file consists of a header, followed by a sequence of tagged blocks of various types. The header consists of a signature, a ''screen descriptor'', and optionally a ''global color table''.
 === Extensions ===
-Block type 0x21 is an ''extension''. Each extension has a byte indicating its type. GIF version 89a defines extension type 0xff to be an ''application extension'', which can be used to store arbitrary data.
+Type 0xff is an ''application extension'', which allows developers to define their own extensions. An application extension's specific type is given by an ''application identifier'' consisting of exactly 8 ASCII characters, plus a three-byte ''authentication code''. Some extensions combine these two IDs to make an 11-byte ID, while others use the authentication code for some other purpose.
-−
-An application extension's specific type is given by an application identifier consisting of exactly 8 ASCII characters, plus a three-byte "authentication code" to reduce the chance of a conflict. In effect, this means it has an 11-byte identifier.
 Known extensions: