Thumbnail format

[aledeg]

Is there a way to choose the output format for thumbnails? I am not talking about the size (I've found the option) but about the file format (PNG vs JPG vs Progressive JPG).
For accessibility purpose, I'd like to have those in Progressive JPG instead of baseline JPG.

[Kwpolska]

No. This could be added quite easily (add progressive=True to the Pillow save arguments here if output format is JPEG) — but is it really worth it for thumbnails? Does it have any negative effect on the output file size?

If there are no drawbacks, we can take a PR making this change.

[aledeg]

Thank you!
I have quite large thumbnails. So yes.
But it's quite a limited use-case.

I won't commit on any PR since my python knowledge is quite limited :)

[aledeg]

I think I've found a way. I used a filter with jpegoptim. In my conf.py file, I've added the following:

FILTERS = {
    ".jpg": ["jpegoptim --strip-all --all-progressive %s"],
}

That works for what I need. It might help others!