I'd like to maintain sng for Cygwin. sng is a markup language and compiler/decompiler for PNG images.
sng is in Debian (https://packages.debian.org/wheezy/sng). It also used to be in Cygwin, until it was obsoleted last year because it depended on libpng12. Thanks to Yaakov for pointing me to the patches from Gentoo that update it to libpng15. With that help sng now builts and runs fine again in Cygwin, x86 and x86_64. Andrew category: Graphics requires: libpng15 rgb sdesc: "Markup language and compiler/decompiler for PNG" ldesc: "SNG (Scriptable Network Graphics) is a minilanguage designed specifically to represent the entire contents of a PNG (Portable Network Graphics) file in an editable form. Thus, SNGs representing elaborate graphics images and ancillary chunk data can be readily generated or modified using only text tools. SNG is implemented by a compiler/decompiler called sng that losslessly translates between SNG and PNG."