Better Portable Graphics: What the New Image Format Can Do

The unique thing about the BPG format is its high compression. It is based on a subset of the High-Efficiency-Video-Coding (HEVC), which is mainly used for video files.

http://www.noupe.com/design/better-portable-graphics-new-image-format-94078.html
http://webencoder.libbpg.org/