libpng(3) on macOS
The text 6d8889a368fa, as Mac OS X 10.6.8, Mac OS X 10.6.7, Mac OS X 10.6.6, Mac OS X 10.6.5, Mac OS X 10.6.2, Mac OS X 10.6.1, Mac OS X 10.6, Mac OS X 10.5.4, Mac OS X 10.5.3 shipped it.
Portable Network Graphics (PNG) Reference Library 1.2.24