I have noticed that rawtherapee produces stange artifacts on red, blue, or violets colors, for certain hues. For a better understanding I put in the following an example:
In this example, it appears blue pixels within the violet area. Actually, this area is only violet. I can have the same issue within red or blue areas
Do you have an idea about the root cause of this problem? How should I solve it? I have tried various dcp profile and it did not solve it…
I put here a link to the raw file. Please, do not publish the face of the kid on the website. NEF_FILE
Thank you in advance for your answers!
olivier
Well I tend to think it is just noise but… did you actually mean that some blue parts should be purple? I do not see any purple (violet) areas, only several shades of blue.
To me it looks like color noise but it seems to be isolated only on the animals body which does seem odd. The outside blues just have typical luma noise. I am not at a computer currently able to test as I am at work but maybe defringing or more aggressive chroma denoise can fix?
This does not look like any artifacting I have ever seen.
As @Claes, @betazoid, and @blj said, it’s the noise combined with very high saturation. If you desaturate the color in question and remove the noise, it will look good again:
Having recently investigated such in other images, I’d agree with @Iain that these are out-of-gamut colors being squashed in a color transform.
I’ve tried to do things like reduce color saturation, and even modify the matrix transform in the camera profile, but if you can’t locally apply such they tend to adversely affect the color in the rest of the image.