out of gamut colors evaluation with just an histogram

[eriksatie]

I was wandering if the histogram is able to show out of gamut colors, and this is why I'm interested in it:

I use Capture One to edit my photos. Capture One doesn't have an out of gamut preview like Photoshop or Affinity Photo. but it has Exp. Warning, and Exp. Warning works also while soft proofing with the "proof profile" option. when soft proofing, for any color that get clipped after conversion in both the right and left side of the histogram you get a warning overlay on the picture. this colors are (from my understanding) out of gamut for the selected ICC profile. when you change the ICC profile for soft proofing, the histogram and the overlayed warning change accordingly.

Now my question is: are the clipped colors all the out of gamut colors, or other colors can be out of gamut but not highlighted by the Exp. Warning? is this method accurate to detect out of gamut colors?

[Simon J.A. Simpson]

The exposure warnings you refer to just indicate where the original camera exposure is clipped, either under or over exposed.

The gamut of a camera indicates the boundaries (and thus the ‘volume’) of colours that it can reproduce.

Gamut and exposure exist independently of each other.

The fact that you see different colours clipped in Capture One is just an indication that either the red, blue, or green channels are clipped before the others.

[digitaldog]

Depending on the Histogram (where and how configured) yes.

Clipping Indicators in Adobe Histograms work out this way:

Black and white = tone clipping (all three channels).
Colors = saturation clipping based on current encoding color space selected:
Red=Red channel
Green=Green channel
Blue=Blue channel
Yellow=Red+Green channel
Magenta=Red+Blue channel
Cyan=Green+Blue channel

[Simon J.A. Simpson]

So, to clarify, the histograms in ACR and Lightroom are showing where the working colour space is clipping the saturation of the red, blue, and green channels of the converted RAW file from the camera.  With ACR it is possible to choose a working space (e.g. sRGB, Adobe RGB, ProPhoto RGB) but Lightroom has only its own proprietary working space ‘Melissa RGB’.  I can’t speak for Capture One.

So, the clipping indicators are not really showing ‘exposure’ at all.

Personally I wouldn’t use these clipping indicators as a guide to in and out of gamut colours.  In any case, I have found they have only limited usefulness.

[eriksatie]

Sorry for missing out the replies, I'm not getting email notification

Capture One Histogram has just the three basic channels, so it doesn't work like the one posted by digitaldog. What is confusing me is that histogram shows clipping (eg out of gamut) only in two dimensions (lows and highs) while gamut is usually described as a three dimensional space. so probably is not telling the whole story.

Basically I'm just looking for a reliable way to check out of gamut colors before printing, but I don't have Photoshop or Lightroom. I use Capture One and Affinity Photo. Affinity Photo has an out of gamut tool, but I don't like how it treats black levels. it just show all the dark areas as out of gamut just because on a particular paper you won't get the level of black (at least this is how I understand it)

[digitaldog]

The 'beauty' of the Adobe Camera Raw histogram shown is you can take action with OOG by altering the encoding colors space. The capture shows color (gamut) clipping because of sRGB and goes away if one picks ProPhoto RGB. Then you render the raw and no OOG.
For printing, OOG is what it is; you can't fit any more toothpaste into that tube. The profiles will map OOG based on the rendering intent. So soft proof, pick the one you like visually, and move on. This is very unlike the stereo on Spinal Tap; it doesn't go to 11.