Editing GIF (section)

===True color===
Although GIF is almost never used for [[color depth#True color (24-bit)|true color]] images, it is possible to do so.<ref name=aminet>{{cite web |url=http://uk.aminet.net/docs/misc/GIF24.readme |title=GIF 24 Bit (truecolor) extensions |author=Andreas Kleinert |year=2007 |access-date=23 March 2012 |archive-url=https://web.archive.org/web/20120316215949/http://uk.aminet.net/docs/misc/GIF24.readme |archive-date=16 March 2012}}</ref><ref name=philhoward>{{cite web |url=http://phil.ipal.org/tc.html |title=True-Color GIF Example |author=Philip Howard |access-date=23 March 2012 |archive-url=https://web.archive.org/web/20150222123613/http://phil.ipal.org/tc.html |archive-date=22 February 2015}}</ref> A GIF image can include multiple image blocks, each of which can have its own 256-color palette, and the blocks can be tiled to create a complete image. Alternatively, the GIF89a specification introduced the idea of a "transparent" color where each image block can include its own palette of 255 visible colors plus one transparent color. A complete image can be created by layering image blocks with the visible portion of each layer showing through the transparent portions of the layers above.
[[File:SmallFullColourGIF.gif|thumb|right|An animated GIF illustrating a technique for displaying more than the typical limit of 256 colors]]

To render a full-color image as a GIF, the original image must be broken down into smaller regions having no more than 255 or 256 different colors. Each of these regions is then stored as a separate image block with its own local palette and when the image blocks are displayed together (either by tiling or by layering partially transparent image blocks), the complete, full-color image appears. For example, breaking an image into tiles of 16 by 16 pixels (256 pixels in total) ensures that no tile has more than the local palette limit of 256 colors, although larger tiles may be used and similar colors merged resulting in some loss of color information.<ref name=aminet />

Since each image block can have its own local color table, a GIF file having many image blocks can be very large, limiting the usefulness of full-color GIFs.<ref name=philhoward /> Additionally, not all GIF rendering programs handle tiled or layered images correctly. Many rendering programs interpret tiles or layers as animation frames and display them in sequence as an animation<ref name=aminet /> with most web browsers automatically displaying the frames with a delay time of 0.1 seconds or more.<ref>{{cite web|url=http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum-frame-delay-browser-compatibility|title=Nullsleep - Jeremiah Johnson - Animated GIF Minimum Frame Delay Browser Compatibility Study|access-date=26 May 2015|archive-date=10 October 2014|archive-url=https://web.archive.org/web/20141010173918/http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum-frame-delay-browser-compatibility|url-status=live}}</ref><ref>{{cite web|url=http://blog.fenrir-inc.com/us/2012/02/theyre-different-how-to-match-the-animation-rate-of-gif-files-accross-browsers.html|archive-url=https://web.archive.org/web/20170201034945/http://blog.fenrir-inc.com/us/2012/02/theyre-different-how-to-match-the-animation-rate-of-gif-files-accross-browsers.html|url-status=dead|archive-date=1 February 2017|title=They're different! How to match the animation rate of gif files {{sic|ac|cross|nolink=y}} browsers|date=14 February 2012|website=Developer's Blog|access-date=15 June 2017}}</ref>{{better source needed|date=March 2015}}