help needed with jpg produced by darktable

I’m using darktable to process my raw photos and save the final jpg’s. I’m on ubuntu linux.

From some of the jpg’s, gthumb gets thumbnails which are far lighter than the original jpg, and the same problem happens with nautilus and with the pillow python library.

Here is one of the photos, hoping to understand what’s the problem with it.

and here is how the thumbnail looks like:

light thumb

What color profile are you exporting your jpeg with?

Also can you post the actual question here instead of a link to stack exchange?

I had a similar issue. In my case it was connected to the color profile.
Maybe gthumb just ignors the color profile?

What color profile are you exporting your jpeg with?

sRGB (web-safe), I think it’s the default, I didn’t change it. Weirdly, not all of my images show the problem I described, so I suspect some other factor may influence.

Besides that, if a thumbnail has a problem with an app (e.g. gthumb), it has it with all the others, and vice versa.

I checked all my images: some of them have the thumbnails washed out, some other haven’t.

All of them have sRGB as output profile, however, the jpg’s whose thumbnails are washed out have color profile “PQ REC2020 RGB”, which is the input color profile of the raws in darktable.

So it looks like darktable sometimes (depending on what?) doesn’t honor the output color profile…

And actually I began having this issue recently, surely not before 3.2.1

You should change your input profile back to the color matrix profile.

the color profile in the jpg export options had been inadvertentely changed.

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I was just about to ask…leave it at image setting then it will conform to what you set in images… unless you have need to change it