[Image-SIG] Docs for decoder

[Fredrik Lundh]

Alden Lavizzo <ALavizzio@quark.com> wrote:
> Is there any documentation on writing a decoder?  I am writing a decoder
> that decompresses a special type of image and cannot find any help on how to
> do this other than looking at source code.

really?  before you do, you might wish to read
the "writing your own file decoder" chapter in
the handbook.

http://www.pythonware.com/library/pil/handbook

it describes how the file format plugins work.
if you cannot use any of the built-in low-level
codecs, things get a little harder.  I suggest
that you take a close look at the raw codec.

if you find it too hard to write an incremental
decoder for your format, an easier solution is
to overload the "load" method and load the en-
tire image in one go (you still have to implement
register your plugin as usual, and implement the
_open method, but you don't have to set the tile
attribute).

</F>