Nearly Blown Out Pixels Showing Up Pinkish

Previewing photos in Rawtherapee and Paintshop Pro and MS Photos shows barely discernable details in nearly blown out cloud pixels. Darktable when opening up shows them as various shades of pink. When I go back in history step 9 exposure I click on it and the pink goes away. I go back one more step to number 8 color calibration and pink comes back. Go to step 10 and pink comes back. Any ideas if one of my defaults is screwed up
20231002-123609-IMG_1617.CR2 (24.4 MB)

For a quick fix, just lower the threshold in the “Highlight Reconstruction” module to around 0.95


Perfect thank you!!!

Those areas have some clipped channels.
If you check the EXIF info, you’ll find:

Normal White Level              : 11767
Specular White Level            : 12279
Linearity Upper Margin          : 10000

But in darktable, the raw black/white point module uses a higher white value, 14200:

This means the highlight recovery tools do not recognise blown channels as such; turning on the raw overexposed indicator does not mark them:

I had to drop the white point to 13584 for green (indicating a blown green channel → resulting in magenta after white balancing) to show up. With highlight reconstruction turned off, I still had areas which were not marked, but showed up as magenta:

At 13583, all magenta areas were correctly marked as having a clipped green channel.

In fact, with highlight reconstruction on (even with the threshold set to 1), the magenta was gone at 13734, which is not that far from 0.95 * 14200 = 13490.


Unsolecited Play Raw :slight_smile:

20231002-123609-IMG_1617.CR2.xmp (10.7 KB)

1 Like

You have got good answers here. But if you want more information this has been a common topic with numerous threads referring to magenta highlights. Personally, I just lower the threshold in the highlights reconstruction module. The amount needed seems to vary so I am reluctant to give a number to use. I keep the threshold as high as I can get away with. Move the slider slowly so you give DT time to recalculate the reconstruction.