I feel confuse about "UJPG" in the code...What does it mean?

dropbox / lepton

Lepton is a tool and file format for losslessly compressing JPEGs by an average of 22%.

https://blogs.dropbox.com/tech/2016/07/lepton-image-compression-saving-22-losslessly-from-images-at-15mbs/

Apache License 2.0

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I feel confuse about "UJPG" in the code...What does it mean? #128

Closed xiaoxiongli closed 4 years ago

xiaoxiongli commented 4 years ago

I feel confuse about "UJPG" in the code..., it seems that "UJPG" stand for "uncompressed JPEG", but what does "uncompressed JPEG" stand for? it meas YCbCr data or something else?

xiaoxiongli commented 4 years ago

Dear @danielrh , Please help ... ^_^, i feel confuse about 'UJPG', thank you very much

danielrh commented 4 years ago

The idea is that the JPEG has been uncompressed into its frequency space components but the header is persisted in a uniform way. This was largely used to test lepton's (and uncmpJPG's https://github.com/packjpg/JPEG-Developers-Package ) ability to roundtrip jpeg files