The GIF89a image file format supports Application Extension blocks, which are used for "application specific" information. These blocks may be used for tagging images with ICC profiles.
The Application Identifier for an embedded profile shall be the following 8 bytes: "ICCRGBG1". The Authentication Code shall be "012". The entire profile shall be embedded as application data, using the conventional technique of breaking the data into chunks of at most 255 bytes of data.
Rationale:
GIF is one of the most common image formats found on the Web. Empirical results show that application of color management techniques improves the quality of resulting image, even in the face of dithering browsers. Therefore, a standard for tagging GIF images would be of benefit to the Web and color communities.
The proposal above specifies a syntax for tagging GIFs. Please refer to the paper "Improved Color for the World Wide Web" on the ICC web site<http://www.color.org> for a discussion of the complexities of the GIF grammar and the difference between tagging a global color table and a local color table. Given the current grammar, it is not possible to assert that the tag always precedes, or always follows, the color table. However, it is not very difficult to write software that accommodates this. This extra effort seems preferable to attempting to
change the GIF grammar and breaking most existing applications.
