lodepng, a smallish png codec, has been updated to incorporate modest png-editing capabilities. I've made some small changes to the encoding interface as well.

http://www.dsource.org/projects/scrapple/wiki/LodePngLibrary

Some minor work still needs to be done, but it is mostly complete and functional.

Thanks to Stewart for bugfixes and help. Also, sorry that it took me so long for these updates.