libavif
Library for encoding and decoding .avif files
...The API is straightforward, allowing applications to integrate AVIF support natively — creating, decoding, compressing, or decompressing images programmatically. Recent developments have added experimental support for HDR gain maps, improved color-space handling (including wide color gamut and high bit depth), and better quality tuning modes for encoding, making libavif a cutting-edge tool for high-quality image compression.