Color Management, Windows; hardware-LUT or not?

Hey, this is the first time for me that I can use a real monitor calibration at home. Now an .icm is created for me, which also contains a hardware LUT for the graphics card.

When this is active, my colors are totally warm. If that is not active and I only activate the profile in RT, the differences are not that big.

I ask because CM is a difficult topic that often gets stuck at some point.

I have:

  • camera using AdobeRGB (there is no need to calibrate the camera colors)
  • monitor-calibration with h-LUT (.icm file)
  • RT (the profile to set here)

What is the right color management to work in RT now and how to save the file correctly for further processing (third business)?

Should Windows get the .icm, and RT none?
Or should RT now become AdobeRGB for my camera?
Or should RT get the .icm and Windows none? But this way, the h-LUT will not be set?

I am using Spyder X from Datacolor, with Spyder X Software @ Windows 10. Is this ok or should i use DisplayCAL I’ve read here that DisplayCAL is very good and elsewhere that it’s very slow and probably sub-optimal on Windows.

My second option is to switch to linux for processing RT, but I don’t know now that the well-known agencies do it that way because the color management is better for publishers (where Apple maybe dominant and at the same time unclear in color management). So i think, Windows is good to go? …

The color space, styles, etc. in the camera apply to JPGs, not raw files, so it’s not a factor. I want the largest color space I can get when processing, so ProPhoto is my raw working space. I also export to TIFF as ProPhoto since I do resizing, exports and final edits in a bitmap editor (where ProPhoto is also my default). I don’t go down to sRGB until the final web JPG export.

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Oh, yes, you are totally right.

The colors I get from the sensor don’t need to be calibrated at the end as it’s all just about finishing on my screen - it’s just the photos I take with my ideas about the colour they should have.

I use the Spyder software and it seems to work fine. It should load the profile it created automatically I think, then at least in darktable, which I use, one also selects the profile to use as display profile.
I hope I’m right on this!
To check if your colors are really too warm I’d suggest taking a photo of something neutral, then doing auto white balance on it in RT then consider if it looks neutral or not, preferably after leaving the PC then returning.

By the way… Where to set ProPhoto in RT? Does it have a special naming? I didn’t found it.

It should be on the list in the Color Management section, but I’m not at my computer right now. I’ve added a few profiles to RT but I think ProPhoto comes with it … I think you can download a set of profiles that includes it.

So it probably makes sense to use ProPhoto in RT one way or the other, because the 32-bit calculation can possibly expand the color space in general? Since ProPhoto is the largest special color space here, I wonder if it might require extremely special cameras.

What is about the monitor? Without having a ProPhoto monitor it does make sense? Are there much monitors available which have ProPhoto?

So, when having ProPhoto, and a third business does not have ProPhoto printers or machines, there is not a lag in smaller color spaces? You cannot downsize a bigger to a smaller space or how does this work?

Your missing the point a bit again…your sensor measures light… 12 or 14 bit likely… color spaces are defined based on a set of primaries with different gamma and gamut. THere is no prophoto camera…You have a number of profiles… the idea in most raw processors is keep as much of the gamut available until you have to drop it down to your intended output…

The color space, whether working (in RT) or export (in the file created by RT) is simply a set of “boundaries” that define the (number and hue of) colors that can be used. The larger the color space, the fewer issues there will be with out-of-gamut (i.e., “unusable”) colors. That’s functionally independent of what the sensor captures*, what your monitor can display, what your printer can output, etc. They all have their limits but they’re independent of each other. In general it’s preferable to have devices that can handle as many colors as possible (i.e., have as large a gamut as possible), but they each have their own.

* A @priort pointed out, the concept of a color space doesn’t apply to a sensor - It’s just a light capturing device. It’s after that captured light is converted to an image that color space comes into play.

By using a color space (at any given point in the workflow) that’s large enough to “contain” all the colors output from the previous step in the workflow, no conversions are necessary. There’s really n downside to using a large working color space. Having a color space that’s too large isn’t a problem – It’s having one that too small where troubles arise. As an analogy, you can pour a teacup of water into a swimming pool without issues, but not the other way around.

I recommend reading this: Tutorials on Color Management & Printing, in particular the " From Camera to Display to Print" section.

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RT comes with ProPhoto and it’s can be found in the Working Profile list. What’s found in the Output Profile list…


…includes anything you add to the directory specified in preferences:

I don’t remember offhand if by default RT puts a ProPhoto profile there, but like I said it can be downloaded (as an *.icm or *.icc file) and put into that folder.

There are ways to do this…

I’ve been trying to understand this for a long time, but I can’t draw it on paper yet :slight_smile:

@lphilpot Thanks for the help. I will read the tutorial. I’ve also read RT RawPedia (great) a lot across, but it’s the first time I’ve gone so much into the detail of the color :slight_smile:

Me neither :face_with_spiral_eyes:… I found this book rather interesting though. It starts with the bare-bones and shows how we come to gamuts and all this stuff. I think someone pointed me to it but I’ve forgotten who. Nicely written IMO.

Thank you very much

@priort @lphilpot

So please tell me, what calibration and software are you using, have you set the hardware LUT to your graphics card and what have you set in RawTherapee for this?

I use ART, not RawTherapee, but they’re obviously very similar. I have ProPhoto as both working and export color space. I don’t mess with LUTs. I’m on Windows now and I use a SpyderX with their software. I’ve used DisplayCal in the past on Linux but so far I’m good to go on Windows with the DataColor software.

What is ART?

Ah ok the search engine only gives a good tip in combination with rawtherapee vs ART and now i got it

I mostly us DT and I only have half the equation. I calibrate the camera with my spyderchecker color card to get an input icc file for DT but I dont’ have a calibrated monitor. For now until the day I get a device to calibrate it I use the monitors sRGB mode as that is usually what I export to most often… It would be better to be calibrated but the output is fine for me for now…
Also if you are trying to understand how it all comes together from sensor to output you could scan this and follow the math or not but even seeing the steps and the flow is informative…