Soft proofing is designed to show you how the print will turn out when using a certain paper profile designed for that printer and paper that you are using. It will be different from when you use a monitor profile. Soft proofing isn't meant to be used with monitor profiles, as far as I know. If your monitor is properly adjusted so that the printer will match what you see, that is what soft proofing is for.
I do understand what soft proofing is. Actually, I'm teaching this to beginners. I'm not using any monitor profile when using soft proofing. I'm just explaining that currently, changing the printer profile does affect the result of Monitor Gamut Warning (top left icon in the histogram), which doesn't make sense, IMHO.
The "out of gamut" colors detected by LR for the monitor (not for the printer) shouldn't change when using a different printer profile. This should be computed by comparing the image in LR's memory (represented in the Prophoto/Melissa RGB color space) and the profile of the display. This should always give the same result whatever the target printer and paper.
The only reason I can think of is that the paper has different capabilities than what your monitor is able to reproduce. The help topic is kind of headlined as showing out of gamut for the monitor OR the printer. Colors that are out of gamut for both the printer and the monitor are displayed in pink. Here's a link to the help page which you may have already read. There isn't a lot of information there.
what rendering intent are you using when soft proofing? You only expect the same result for the monitor gamut warning if you use relative colorimetric intent and if the color is also not out of gamut on the printer profile. As far as I know, the monitor warning is calculated after conversion to the printer profile. perceptual rendering can shift the colors so far that they end up in the monitor gamut. Also clipping of color in the printer profile can shift color into the monitor profile.
Jao vdL wrote:
As far as I know, the monitor warning is calculated after conversion to the printer profile.
Did you read this in some documentation? OK. The only doc I have says:
Show/Hide Monitor Gamut Warning
Colors that are outside your display’s color capabilities appear blue in the image preview area.
which is not very informative. If I don't now which image is referenced when computing the Monitor Gamut Warnings, the feature is useless.
Someone proposed another explanation : selecting a display profile instead of a printer profile would allow to evaluate how the image will be rendered on another display complying with that profile (for example when exporting images for the web, I could test how they will look on a sRGB monitor). I can admit this explanation but in that case, there's something wrong in the user interface: when selecting a display profile, the printer gamut warning should be disabled (as well as the rendering intent) and reversely, when selecting a printer profile, the monitor gamut warning should be disabled.
In any case, Adobe need to be more accurate about this.
The help topic is kind of headlined as showing out of gamut for the monitor OR the printer.
OK but the problem is : what reference is used to compute the out of gamut colors? For the target printer+paper, the reference is necessarily the image currently loaded in LR and represented in the Prophoto/Melissa RGB color space. There's no other choice.
For the out of monitor gamut colors, there are multiple choices:
1. If this feature is here to merely show us what colors cannot be displayed by the monitor, the reference must be the same as for the printer : the image in the Prophoto RGB space. The result should always be the same whatever the selected printer profile.
2. If the reference is the image corrected for the target printer (assuming a printer profile is selected), the result is totally useless (IMHO).
3. If this feature is only here to help us evaluate how the image will look on a monitor complying with the selected display profile, the user interface must be revised : the out of printer gamut has no meaning in that case and should be disabled as well as the rendering intent. Reversely, if a printer profile is selected, the out of monitor gamut visualization should be disabled.
indeed they are vague about this. My thought about this comes from conversing with Adobe folks here and elsewhere as I am pretty sure I'vce discussed this on the forum before. As far as I know the monitor warning is supposed to be calculated after the conversion to the printer profile so that you get an idea whether the soft proofed color is accurately displayed. That shoud be the correct behavior as proofing can actually take a color either in or out of the monitor gamut. I am not 100% sure on this though but it certainly explains how it behaves.
Also if you calibrate your display and write out a icc v4 display profile, the situation changes again as now the display profile can actually contain a perceptual rendering intent, making it even less precise and the assumption of simple one-to-one linear conversions between color spaces is invalid. Few calibration software packages do this though but there are a few exceptions.
If you only want to know whether your image is outside of the display profile, you can indeed trick the soft proof to allow you to select a display profile as the printer proofing profile. You can in principle select a standard working space such as prophotoRGB there and get results that make sense. But you definitely do not want to have a random printer profile selected for the reasons cited above. I guess they could add some smartness to detect that you selected the profile of the current display and not a profile of another random display and then collapse the interface but that is such an edge case that I doubt Adobe would prioritize this. It works fine if you simply realize that you selected your monitor profile as the printer proof profile.
Jao vdL wrote:
As far as I know the monitor warning is supposed to be calculated after the conversion to the printer profile so that you get an idea whether the soft proofed color is accurately displayed.
OK. I'll take this as the most satisfying explanation. Thanks. But if Adobe could be more verbose about this, I'd appreciate.
That seems to be the way it works - and it makes good sense too. This is what you need to know when soft proofing: exactly how much does the monitor gamut limit the usefulness of the soft proof?
A special case that illustrates this, is when you soft proof to your monitor profile. As you crank up saturation, you'll get destination gamut warning as expected. But no matter how much saturation, there's no monitor gamut warning - because it's already clipped to your monitor profile and there can't be anything out of monitor gamut.
When soft proofing, you always need to consider monitor gamut on top of the proof profile, as a check on how visually useful the proof is. And this is a good way to remind you of that.