Save as PNG

I really need to save images as a PNG. does anyone know of a way to do this.
and if not does anyone know where i can learn the format so i can write my own converter.

I think that is called a 'format description'. I found this link when searching for it.
http://www.coolutils.com/Formats/PNG

However, you could try the FreeImage lib. I haven't used it myself, but I read about it on the forum.
Here is a thread about it:
http://www.blitzbasic.com/Community/posts.php?topic=26276

The forum links don't exist anymore. Ill check the description more in detail later, unless someone else knows something better.

Thanks for the reply.

Ow .. okay .. I didn't check it.
Here is the code archive entry for freeimage:
http://www.blitzbasic.com/codearcs/codearcs.php?code=1732
Further down (in the comments) are examples how to use it. I saw that in one of the examples, a PNG is saved. (Ctrl+F search for "png")

If you open the file in paint and go to save as you can convert it to PNG ( along with JPG,BMP, ect.).

This may help - if you want the specification they should be available from here:

http://www.libpng.org/pub/png/

You may have to write your own exporter.

This post contains the version of the FreeImage wrapper I used, complete with required decls.