The -p option (progressive) with jpg input files results in error and no image being put out, even when it is just on its own without any other options. about libjxl HOT 3 CLOSED

Noteworthy for me: the output of the following command (in comparison to without the progressive flag) results in about double the size image and takes about 2x time:
.\cjxl.exe .\Test.png .\result6.jxl -p -q 100 -v --compress_boxes=1 --num_threads=16 --jpeg_reconstruction_cfl=1 --lossless_jpeg=1 --resampling=1 --ec_resampling=1 --already_downsampled -I 100 --codestream_level=10 --group_order=1

(Please do not confuse this note with the reported problem. I did try -p just on its own and with another jpg image).

Kind regards.

from libjxl.

Just for some info, the failed progressive on the jpeg is due to it trying to losslessly transcode it, which uses different techniques than normal and likely is what's breaking it.

The png getting massive and taking longer is because the jpeg transcode is almost instant and skips a lot of steps that normal encoding needs. If you try to compress it with only -d 0 -p then it should be smaller than the png at least, a lot of those options are redundant or for jpeg only.

If you want to progressively encode the jpegs before it's fixed, then try -p -d 0 -j 0 for lossless or -p -d 1 -j 0 for lossy, bear in mind the results will probably be worse than the transcode.

Best for the experts to chime in, but hopefully this explains and helps somewhat

from libjxl.

This should be fixed with #2479

Feel free to reopen if the issue is still there.

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