buggz wrote:I asked about the mapping to the source profiles because I find the "hue color map", top right corner,
a bit confusing.
I'm guessing INP would be profile #1, #3, Display A IN, and Display B IN? This depending on the VIEW selected.
And then I>M is profile INP mapped to the MONITOR current workin icc profile?
Then the OUT is using the opposite of IN, profiles #2, #4, Dispaly A OUT, and Display B OUT. This depending on the VIEW selected.
Yes, that's pretty much got it right. Gamutvision itself is a color managed app. So regardless of what source & target profiles you have selected in slots #1 through #4, much of what it is showing you on screen is, of course, transformed through your own system's monitor profile before appearing on your monitor. If you didn't have a monitor profile or if it had problems, vs. being there and being good, this would impact what you see. Your monitor profile clearly is an active player in how you visualize what is going on with the other profiles that you're actually trying to analyze.
So the I vs. I>M and O vs. O>M options in the upper right give you the ability to take your own monitor profile into or out of the equation during the display of the hue map or various other test images that are rendered up there. The I and O selections give you the "raw take" of the input or output profile's effects on the test image, just dumped straight to your video system without first being color transformed through your monitor profile. The I>M and O>M options do the color transform through your monitor profile first; these are the options you'd use normally assuming your own profile is present and good.
Note that you do need to tell Gamutvision about your own monitor profile; it doesn't pick it up from the operating system and use it automatically. Rather, it defaults to using sRGB if you don't specify anything else. So in the default case the I>M and O>M selections would be showing you the test image first transformed to the input or output profile, and then transformed to sRGB. You configure your own monitor profile using the app's Settings > Monitor Profile menu item.
I am also wondering about the rendering intent options.
I understand the straight forward items:
Perceptual
Colormetric
Saturation
Absolute
none
How do the other differ from the above choices?
The soft proofing choices, in particular.
The remaining choice, round trip, is covered very well on the Gamutvision site.
The rendering intents are interesting. RI plays a bigger part in color management -- especially printing -- than I suspect many folks realize. The 4 basic ones, Perceptual, Colorimetric, Saturation and Absolute, are the same standard RI's found within any color managed app.
The option None is a special case meaning "don't actually do any color transformation"; this is equivalent to the "no color management" setting that used to exist in Photoshop (but doesn't now) or in the printer driver. It's useful for comparing two profiles with each other head-to-head, no transforms. For example suppose you had spent a chunk of change on a new wide gamut display that claimed to support 97% of the Adobe RGB color gamut. You could select Adobe RGB as the input profile #1, your monitor profile as the output profile #2, and set the RI to None. Then looking at the 3D wireframe display, you could display the raw gamut volumes of each profile and see how they compare, verifying the marketing claims of the monitor manufacturer.
You could do the same thing using an input profile of Adobe RGB (say for example that's your standard working profile in Photoshop) and a printer profile as the output profile. With None selected as the RI, this lets you compare the raw gamut volumes of the two profiles. An interesting question this display can answer is, would my printer be capable of printing any colors that lie outside the gamut of Adobe RGB? If the answer is yes, this could be an argument for using ProPhoto RGB as my working color space in Photoshop, so that I can potentially print with those richer hues. This is an actual case -- something again that many folks don't realize is that modern inkjet printers do in fact exceed the gamut of Adobe RGB in certain hues. If you only ever used Gamutvision to evaluate profiles with a RI of Perceptual or Colorimetric (the two most common & useful ones), the tool would always be constraining its diagnostic displays by transforming colors that were originally limited by source profile (Adobe RGB in this example) which by definition means they'd never visualize the extra gamut available in the output profile. You'd never realize there was extra color on the table that could potentially be used in your prints.
Maybe that was obvious but since we're on the topic I wanted to point this out as a special case use of the None RI.
The round trip stuff is covered in the big tutorial at the Gamutvision site, as you say, I won't mention it further for now.
This leaves the 4 soft-proofing selections, each one is an analogue to the 4 basic RI's. This is a bit tricky to explain clearly in words without a lot of examples to illustrate but I'll give it a shot.
The 4 soft-proof RI's are used to account for the point I mentioned above, that your own monitor (including its color profile which may be missing, poor quality, or good quality) is an active player in the color pipeline as you work on images.
Let's say that you've chosen ProPhoto RGB as your working color space in Photoshop because you have a modern DSLR that can capture a wide range of color, you like dealing with a lot of saturation, and you print on a modern inkjet that can do some very saturated colors that lie outside what Adobe RGB can represent. You've had a custom printer profile done up for you by somebody who is a pro at it and has all the great equipment and knows how to use it. This should really ideal -- you shoot your images, process and print them, and should be able to get rich, accurate color across the board, to the maximum supported by both your camera and printer. But for some reason your prints don't look right.
Oh, wait. It's because your monitor is a 10 year old, cheap consumer grade CRT that didn't even have the gamut of sRGB when it was brand new, and since then has gone way out of linearization as the monitor has dimmed over time. Furthermore, you calibrated it, but only using a 10 year old, cheap consumer grade monitor profiling tool that produces bad profiles even on good monitors. This is a problem.
Even though your camera is great, Photoshop is great, ProPhoto RGB is a great working color space, your printer is great, and your custom printer profile is great, the monitor is the weak link in the chain. Everything you do in image processing is viewed through the lens represented by your monitor and its associated color profile.
In Gamutvision, you could do some analysis of why your printing problems are happening. You'd set ProPhoto RGB as the input profile (#1) and your custom printer profile as the output profile (#2). The thing is, the problem is not happening in the transformation of your image in its color space (ProPhoto RGB) to the printer color space. The problem is happening in between because your monitor is causing you screw up the image during post-processing in Photoshop by giving you a bad view of the image and its color. Even though everything else is right, the monitor profile throws the whole thing off the rails.
Long and extreme, contrived setup
but this kind of thing is what the 4 soft-proof RI's are designed to help identify. If you pick the Perceptual RI, in this example it will show what happens to the image color going from ProPhoto RGB to the printer profile. But if you pick the Perceptual soft-proof RI instead, it's going to show what happens starting from ProPhoto RGB, then getting clipped down & screwed up by the monitor's limited & messed up color space, and then going to the printer profile. This kinda simulates the 3-way relationship involved in printing the image, but only after you have been looking at it & working on it using your monitor which is well below par compared to both the input and output profiles. If the monitor (or its profile) has a big problem, it can show up using these soft-proof RI's even though the monitor profile itself is not selected as either the #1 or #2 profile in the Gamutvision view.
If you want to experiment with these soft-proof RI's, this is a good example of why Gamutvision has 4 profile slots, two for input and two for output. It's so that you can pick the same input profiles in #1 and #3, and the same output profiles in #2 and #4, but choose 2 different RI's. E.g. compare the impact of choosing Perceptual vs. Colorimetric -- for printing this can be a substantial impact. Likewise if you think the monitor may be influencing your post-processing work, then compare Perceptual vs. Perceptual soft-proof; or Colorimetric vs. Colorimetric soft-proof. If you don't really see any major differences between the normal RI and the soft-proof RI it's one piece of evidence that your monitor is not really tripping you up. But if you do see differences between the soft-proof and normal RI's, then it would indicate there's something to look at more closely about how your monitor (or its profile) is impacting your whole color managed printing workflow.
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