After publishing pngsmuggler last week, I was unsatisfied with the wasted green channel, so I went back and adjusted the encoding and decoding to handle it.

And, it occurs to me that since you can put just about anything in a png, you can put the source code of your projects in there. So, here's PNGSmuggler, in a png:

Source of utility, and the PNGSmuggler class are here