A little more detail on Gif
Created | Updated Mar 10, 2004
A Bit more about the Gif in files.
More details of the Gif file type.
There is a kind of packet structure present in image files. There is global information about the file, the version number, the screen size and color palette. There is an enclosed packet defining the image properties as a header for each image.
The Gif file can contain more then one image. The Gif file can contain text, comments and special application extensions.
According to the documentation offered by CompuServe, all technical explainations about applications using Gif files, should contain the following statement.
"The Graphics Interchange Format(c) is the Copyright property of
CompuServe Incorporated. GIF(sm) is a Service Mark property of
CompuServe Incorporated."
Unisys is owner of the 'Variable-Length-Code LZW Compression' algorithm, it is free for anyone to use the code. It is not free to write a commercial application using the algorithm, those writers have to get hold of a licence.
(We still claim the equation algorithm. The BBC wishes to own the LINK tag, etcetera.)
Anyway, as far as I understand I am allowed to publish an interpretation of the Gif89a Specification.
Global Gif File Packet components
The Gif file is completely modular, the file should contain blocks made of a Header, the Payload and a Trailer. The Headers have two structures, there is a global header and there are sub headers. The Payload can contain one image, more images, texts, comments and application extensions. The Trailer is a one byte code, closing the packet at or after the expected byte.
Hmm, still very cryptic, I will make a table drawing for it.
