XnView Software

Just to give it the acid test I repeatedly saved, then opened and re-saved a JXL file with no edit as a JXL file in Affinity. Each time the size of the file was every so slight different. Strongly suggesting that the Affinity JXL routine does not meet the JPEG Committee (ISO/IEC JTC 1/SC 29/WG 1 ...

I have done three rounds of converting TIFF to JXL, then JXL to TIFF. Each time I take the proceeding output file and use it for the other format.

The results are in...

With XnConvert, no matter how many times one takes one format and convert it to the other. Then takes that output and converts it ...

A friend was convering a 545 MB TIFF to JXl in Affinty and got a 81 MB. We both assumed that when Affinity said "100% Quality" export it meant Lossless. Now I think it means "visually lossless", i.s.lossy.

Lossless with XnConvert was 368 MB. I tried a variety of combinations for 99% to 95% quality ...