|Python Imaging Library Handbook|
PIL reads GIF87a and GIF89a versions of the GIF file format. The library writes run-length encoded GIF87a files. Note that GIF files are always read as grayscale ("L") or palette mode ("P") images.
The open method sets the following info properties:
Default background colour (a palette colour index).
Time between frames in an animation (in milliseconds).
Transparency colour index. This key is omitted if the image is not transparent.
Version (either "GIF87a" or "GIF89a").
The GIF loader supports the seek and tell methods. You can seek to the next frame (im.seek(im.tell()+1), or rewind the file by seeking to the first frame. Random access is not supported.
The GIF loader creates an image memory the same size as the GIF file's logical screen size, and pastes the actual pixel data (the local image) into this image. If you only want the actual pixel rectangle, you can manipulate the size and tile attributes before loading the file:
im = Image.open(...) if im.tile == "gif": # only read the first "local image" from this GIF file tag, (x0, y0, x1, y1), offset, extra = im.tile im.size = x1-x0, y1-y0 im.tile = [(tag, (0, 0) + im.size, offset, extra)]