Source of PNG++

[[PNG]] > [[libpng]] > [[PNG++]]

- https://www.nongnu.org/pngpp/
- http://charette.no-ip.com:81/programming/doxygen/libpng++/
 
- [https://www.hiroom2.com/2014/05/28/libpng%E3%81%AEc-%E3%82%A4%E3%83%B3%E3%82%BF%E3%83%BC%E3%83%95%E3%82%A7%E3%83%BC%E3%82%B9%E3%81%A7%E3%81%82%E3%82%8Bpng-%E3%82%92%E4%BD%BF%E3%81%A3%E3%81%A6%E3%81%BF%E3%82%8B/ https://www.hiroom2.com/2014/05/28/libpngのc++インターフェースであるpng++を使ってみる]