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Comment by daniel_rh | Hacker News Reader

Thanks for testing this! For archival purposes, be sure to check the exit code of the lepton binary after compressing each JPEG: the default parameters only support a subset of JPEGs (you need to pass -allowprogressive and -memory=2048M -threadmemory=256M to support a wider variety of large or progressive JPEG files). Lepton will not write images that it is unable to compress using the settings provided. In those cases be sure to keep the original JPEG.

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Hi Daniel, very cool project! I am interested in hearing your thoughts on alternative image formats / compression methods.

WebP is very promising (also based on VP8) for lossless and lossy compression. Have you considered using it to compress PNGs in the same way Lepton is compressing JPGs? Odds are it wouldn't be bit-perfect though (despite being pixel-perfect).

Also interested in hearing about the tradeoffs between server-side decoding and client-side. Not to keep focusing on it, but WebP has native support in Chrome and javascript decoders for everything else.

I think it is a very exciting time for image formats with several promising new ones on the way (WebP, FLIF, maybe BPG but possible legal issues).

How much better do you think it could get with JPEGs encoded with Lepton in mind?

The best I've seen is a new compressor at http://encode.ru/threads/2459-EMMA-Context-Mixing-Compressor

Can also recompress GIF and some RAW formats, but is much, much slower

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