WebP
WebP is a free image file format first released by Google in 2010. It consists of 2 primary “modes” of operation. A lossy mode derived from the VP8 video codec, and a novel lossless mode added in 2011.
Encoding
Using libwebp
libwebp supports WebP, JPEG, PNG, PNM (PGM, PPM, PAM), TIFF as input formats, and a quality (-q) value between 0 (lowest quality, smallest file) and 100 (highest quality, largest file). Should you need the lossless mode, you need to instead use a -z argument, with values representing the effort used between 0 (fastest encode, largest file) and 9 (slowest encode, smallest file).
cwebp example.png -q 75 -o example.webpPerformance Checklist
Lossless? Yes
Lossy? Yes
Supported Bit Depth: 8 BPC
HDR/Wide Gamut? No
Animation? Yes
Transparency? Yes
Progressive Decode? No
Royalty Free? Yes