Re: A generic image decoder - specification design

[Gautier write-only <gautier_niouzes@hotmail.com>]

Thanks for the feedback.
The project is really restricted to decoding images of the broadest
spectrum of formats and do whatever the user wants to do with the
pixels: store into a buffer (and process, save, or save that buffer),
or display them directly in a GUI object, or whatever else...
The current state so far is:
* BMP is done, except RLE compression and some unusual bit depths
* GIF is complete (including animated pictures)
* PNG is covering all but transparent formats; there is a nasty glitch
    with the decompression, so it works on some pictures and on some,
not...
    up to now I was able to have a common source for all formats;
    sure, I should have a closer look to PNG_IO...
* TGA is on a good way to be complete

You can have a look via a svn checkout:
svn co https://gen-img-dec.svn.sf.net/svnroot/gen-img-dec gid
and with gnatmake -P gid.gpr
It builds ./test/to_bmp on your platform.
Note: there is a "Fast" mode in the gid.gpr project file!
Gautier


On May 24, 10:51 pm, Stephen Sangwine <s...@essex.ac.uk> wrote:

> Interesting idea. What you are proposing looks to me like a sort
> of binding to various image libraries, in that you provide basic
> image reading/writing to a variety of formats. Of course, you
> can't handle all the special features of each image format, but
> for an application that just needs to read or write the pixels
> and a few other basics like palettes, alpha etc, the approach
> would be useful. I can speak from experience of developing PNG_IO
> to say that handling any non-trivial format is not a small task.
> BMP is pretty easy - TIFF is probably the hardest to handle. In
> both PNG and TIFF the pixel data is stored in disparate pieces
> within the file - not as a single block of pixel data. In the
> case of PNG the compression runs across these blocks, not within
> each block. What this means is that code for handling the pixel
> data can't easily be common to different types of image file.
>
> You have available an Ada package for PNG already in PNG_IO.
> I've thought about GIF as a student project now that the
> compression is no longer subject to patent protection, but no
> work has been done on it yet.
>
> Steve Sangwine