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A comment on J40: Independent, self-contained JPEG XL decoder. Parent comment

Re:J40: Independent, self-contained JPEG XL decoder by userbinator on Sunday September 18, 2022 @05:13PM (#32891568)
Are you familiar with JPEG2000? I looked at this diagram of JPEG XL and was overwhelmed at the complexity, it seems more complex than J2K baseline:

https://en.wikipedia.org/wiki/File:JPEG_XL_codec_architectur...

...and I say this as someone who has written PNG, GIF, and JPEG (baseline sequential) decoders, and didn't think J2K would fit in 5kLoC either.

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Re:J40: Independent, self-contained JPEG XL decoder by lifthrasiir on Sunday September 18, 2022 @05:54PM (#32891852)
I think the exact code for features in that diagram does fit in 5K lines of code. More specifically an entropy coder is less than 1K LoC, the modular mode and transform is probably 1.5K LoC, the entirety of VarDCT is probably 2K LoC. The problem is that JPEG XL has a lot of other features to make it viable as a long-term format, and I greatly underestimated that complexity at the beginning.
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