Lightroom 6.0.1: Wrong RGB values in softproof histogram (LR4 and LR5 were correct)

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  • Updated 3 years ago
Create a simple image in sRGB color space with some "blobs" with colors e.g. (RGB) 255/0/0 (pure red), 255/255/0, 0/255/0, 0/0/255 etc. Then import the image into Lightroom 6.0.1 or its CC equivalent.

Now activate the softproof and select sRGB as the target profile. Move the mouse cursor over the different colors and observe the RGB values under the histogram. In LR4 and LR5, these values very closely (if not exactly) resembled the original RGB values of theoriginal "blobs" drawn, as one would expect. In LR 6.0.1, the RGB values are totally off.

Interestingly, the RGB values in the histogram remain the same when selecting AdobeRGB or ProphotoRGB as the target profile. Again, in LR4 or LR5 they would change accordingly then. Note: The RGB values do become different when selecting a printer profile.

Some examples (original sRGB values -> LR histogram display in sRGB softproof):
255/0/0 -> 135/25/4
0/255/0 -> 84/223/30
0/0/255 -> 36/7/221

Edit: OS is Windows 7, GPU acceleration on/off does not matter.
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LRuserXY

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Posted 3 years ago

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Steve Sprengel, Champion

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Do the numbers change if you change the display profile, perhaps from sRGB to AdobeRGB?

I am talking about changing what your monitor's display profile is and restarting LR or maybe restarting your computer as well.
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LRuserXY

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That's the strange thing: They don't change when selecting AdobeRGB or ProPhotoRGB, but they change when using a printer profile.

In LR4 and LR5 everthing worked as expected: Softproof to sRGB showed the original sRGB values. Softproof to AdobeRGB and ProPhotoRGB showed different values, with the "main" color channel, e.g. red, reduced or the other channels increased - more pronounced in ProPhotoRGB, as expected.
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LRuserXY

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Update: When softproofing for a printer profile, the RGB values still differ dramatically between LR4/5 and LR6, so something seems to be wrong in general with the softproof histogram RGB values, not just for special cases like sRGB, but also for completely normal raw images.

Note: The histogram itself seems to be ok (no difference compared to LR4/LR5). Only the RGB values are affected.