From the course: GIMP Essential Training

Work with color-managed documents - GIMP Tutorial

From the course: GIMP Essential Training

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Work with color-managed documents

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- [Instructor] GIMP's color management features were expanded version 2.10, giving you more options for working with color-managed documents. And while color management is a deep topic that goes beyond the scope of this course, I do want you to understand the basics of working with color-managed files, and in particular, what to do when you see a color management dialog box in GIMP. So in the exercise files, let's open a file called Hot_Rod_AdobeRGB. And we get a dialogue box asking if we want to convert this image to the RGB working space. Without going deep into color management, I can tell you that a working space is similar to a color profile. It's a particular version of RGB that GIMP assumes for new documents and for documents that don't have a different embedded color profile. Color profiles are necessary because every device is different. Computer monitors, phone screens, cameras, scanners, and printers all have different capabilities for representing color. So to get accurate, consistent color throughout your image workflow, it's not enough to just say that an image is RGB. GIMP needs to specify which version of RGB it's working in. And by default, the version of RGB that GIMP uses is sRGB. And that's a good choice, since it's the version of RGB that's best suited for working on images for the web. Now, the main choice in this dialogue box is between Keep and Convert. If I keep the existing profile, the RGB values in the file will not be changed, but the colors in this file won't match those in another file with a different embedded profile, even if they have the exact same color values. If I choose Convert, I am changing the RGB values in the file in order to keep the color appearance the same when I'm working in the sRGB working space. The thing that makes this confusing is that either choice you make here will not effect how the image displays onscreen in GIMP. It's only the underlying RGB color values that will either be left alone with Keep or changed with Convert. In general, if you don't have a color-managed workflow, I'd recommend that you go ahead and convert to sRGB. That way, you'll be consistent, using the same working space for all your images. On the other hand, if maintaining specific color values in the file is of critical importance, then go ahead and choose Keep. In this case, I'll convert to sRGB and leave the choices for Rendering Intent and Black Point Compensation at their defaults for best results. You only want to change these if you know you have a specific reason for doing so. Now, there are two more things that I want to point out that have to do with color management. One is in Preferences, which is under the GIMP window here on Mac or Edit in Windows. Here, you'll find a whole group of color management settings that you can use to build a color-managed workflow. And if you scroll down to the bottom, you can decide what happens when you open a file with an embedded color profile that's different from your working space, right here under Policies. The default is ask what to do, but you can set it to always keep or always convert. And in Preferred Profiles, you can also specify other profiles to choose from besides the built-in sRGB. Also, in the Image menu, you can choose Color Management, and apply the same Convert to Profile command that we saw in the dialogue box. Or you can assign a different color profile to an image. Doing this does not change the color values in the image, but it can change their appearance onscreen, because you're telling GIMP to interpret those color values differently. And you can choose from the color profiles you have installed on your computer in the popup menu. So here we took a very brief look at working with color-managed files in GIMP. We saw the dialogue box that allows us to keep embedded color profiles or convert to the working space. We also saw the color management preferences and the commands in the Image menu for assigning and converting to color profiles. If you want to explore color management in more depth, there are courses in the online library that go into detail on topics like color profiles, calibrating your monitor, and soft proofing to simulate specific output conditions for your images.

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