Dealing with out of gamut colors (and filmic)

I’ve been struggling with out of gamut or overexposed files lately.

Attached are three files:

The first one is partly overexposed on the colorful highlights. Highlight recovery helps some, as does switching the input profile. But as soon as I activate filmic, colors go all over the place, producing gray patches where there should be bright color. Setting preserve chrominance to “luminance Y” helps, but still looks unnatural.
Screenshot_20200125_155801
GR035381.DNG (16.6 MB)

The second file has two colored lights shining right at the camera. And this time, no chrominance preservation saves the image; they just introduce different kinds of errors (grey areas or black areas). But this time, a simple base curve saves the image without problems. Is this a bug in filmic?
Screenshot_20200125_160346
DSCF0064.RAF (16.2 MB)

The third image might be pathological. This time the sky is an extremely bright yellow, which apparently doesn’t clip the RAW, but certainly is way out of gamut. The problem is, it renders as magenta, or a subdued gray, where by all rights it should just be plain white.


DSCF0902.dng (76.2 MB)
But I say it’s maybe pathological, as this file was produced by the Iridient X Transformer from a Fuji RAF file, and the RAF file itself does not exhibit the problem to the same extent. So this might be more a problem with the X Transformer than with Darktable.

Any pointers on how to deal with these kinds of images would be greatly appreciated!

I would call it over exposed or even clipped

hi @bastibe

@anon41087856 had similar problem with blue LEDs :

Maybe that can help you.

Note that the files from X transformer are probably not raw, but just a dng with a tiff inside, so darktable will not be as effective on these files.

It’s demosaiced, slightly denoised, and sharpened. But the values are compatible enough that I can copy and paste edits from the original RAFs to the X-Transformer’s DNGs without seeing any visible difference (except being sharper). So at least they’re still linear.

Do you think that this process would still effect color processing?

I must apologize. As it turns out, this was a bug in the git version of Darktable. The stable version does not do this. Sorry for the mess.

If the bug’s present in current master - please send devs the report + reproduction steps so nobody else’s going to hit it if it’s fixed :slight_smile:

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