Forced progressive JPEG encoding would further reduce file size for the vast majority of non-progressive JPEGs

[damian101]

By default jpegoptim keeps progressive JPEGs progressive and non-progressive JPEGs non-progressive. But unless images are extremely small, progressive encoding normally results in smaller file sizes. Most cameras encode non-progressively because it's less ressource-intensive and is much easier to do in hardware. Those images are currently not optimally compressed by Trimage.

I think just adding "--all-progressive" to the jpegoptim command would be an improvement.

[Kilian]

I didn't know (Or I did and forgot), that's interesting! I need to think if I consider switching to progressive JPEGs to be "lossless".