Lepton is a recompression format specifically for JPEG. It's lossless in the sense that you can reconstruct the input JPEG perfectly, but of course JPEG is itse

Lepton is a recompression format specifically for JPEG. It's lossless in the sense that you can reconstruct the input JPEG perfectly, but of course JPEG is itself an inherently lossy format. FLIF is a lossless image format. It's not a good idea to give it an ex-JPEG file as input, just like it's not a good idea to convert JPEG to PNG, because it will need lots of bytes to losslessly compress all those JPEG artifacts that JPEG gets for free :).