Free Lossless Image Format (FLIF) is a work-in-progress lossless image format claiming to outperform PNG, lossless WebP, lossless BPG and lossless JPEG 2000 in terms of compression ratio on a variety of Inputs. FLIF supports a form of progressive interlacing (a generalization of the Adam7 algorithm), which means that any partial download of a compressed file can be used as a reasonable lossy encoding of the entire image.