Artifacts when using Dynamic range reduction in RawTherapee

I’ve edited some images from yesterday in Black and White and noticed something strange in the shadow areas.

It is the salt and pepper noise you can see on the heads of the people in the lower side of the image. I will upload the raw file and the pp3 as well. it turns out if I disable dynamic range reduction it goes away.

S7_00463.ARW (46.8 MB)
S7_00463.ARW.pp3 (12.0 KB)
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Does that also happen in ART?

It seems to be caused by the amount of Detail preserved and then processed by the tool.

If you turn Dynamic range off, and raise Exposure to +6, you will see a similar salt and pepper effect on those areas (caused by noise, or maybe some details in dark shadows).

Keeping the Dynamic range off, and turning on Shadows/Highlights, with Highlights 70 - Highlights tonal width - 45 you will get a better rendering (intentionally a bit darker, to lower the white values on the ballerinas). Setting a different Highlights tonal width will change the values on the stage, without affecting the dark shadows that are bothering you.


I have no idea

Ok, I will discuss this with @agriggio tomorrow