question: is progressive encoding supported?

lifthrasiir / j40

J40: Independent, self-contained JPEG XL decoder

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Open palmerabollo opened 2 years ago

palmerabollo commented 2 years ago

Thanks for this project.

Reading the README it is not clear to me whether progressive JPEG images are supported. Could you please clarify that?

(I'd like to try this lib it in a ESP32 with limited resources, where adding many dependencies is problematic).

lifthrasiir commented 2 years ago

Your question can be interpreted in two ways, and the answer for both questions is "right now, no" but for different reasons:

Progressive JPEG images are treated like an ordinary JPEG image when libjxl transcodes them into JPEG XL (they can be losslessly reconstructed, but it won't be progressive unless -p is given to cjxl). J40 can't yet handle any such transcoded images (#5).
J40 currently doesn't support any progressive image encoded with cjxl -p (#4).