Out of Gamut: Setting Up Color Management in Photoshop 6
As somebody who spends much of his time writing about, thinking about, or practicing color management, I often hear one question: "How can I make my prints match what I see on my monitor?" The short answer, though it's the one that those in the business of selling color-management tools never seem to give, is that you can't. Your monitor is capable of displaying many colors that most printing processes simply can't reproduce.
The reasonable next question becomes, "But if you can't make your prints match your monitor, what's the point of color management?" The answer is that color management can help you get an accurate preview, on your monitor, of how the images will appear in print. In other words, it can make what you see on your monitor match your prints.
The general principle here is that you can always make something with a large color gamut (your monitor) simulate the behavior of something with a smaller one (your printer). That's the whole point of Photoshop's Proof Setup feature: It lets you see on your monitor how your image will appear in print, and make any necessary edits to improve it.
Getting onscreen proofing to work, however, isn't trivial. It depends on the accuracy and proper interaction of three profiles: the image's profile (which tells Photoshop what colors the numbers in the image represent), the monitor profile (which Photoshop uses to tweak the data it sends to the display, so that it produces the colors represented by the numbers in the image), and the printer profile (which tells Photoshop what colors your printer can print, and which numbers it needs to be sent in order to print them). (If all this talk of profiles is confusing, check out "Out of Gamut: Getting a Handle on Color Management.")
In short, if you want color management to work for you, there are a number of things you need to do before you even think about making prints. The good news is that none of these tasks is difficult on its own. Setting up effective color management simply takes a bit of forethought and work.
Calibrate Your Monitor
To give color management any sort of try, your first step should be calibrating your monitor. This is a necessary and crucial step -- not a mere nicety or some hair-splitting indulgence you'd allow yourself in an ideal world. Your monitor is the window through which you view all your color, and to generate the results you want, your color-managed applications must have an accurate indication of what color your monitor displays in response to a given set of RGB numbers. The only source your applications have for this information is the monitor profile, and it needs to be accurate if you want to see and specify color at all accurately. Without a reasonably accurate monitor profile, it's pointless to go any further.
If you're serious about trusting what you see on the monitor, an instrument-based calibration package such as ColorVision's PhotoCal or OptiCal, or GretagMacbeth's Eye-One is a worthwhile investment, because it will take the guesswork out of the process, but prices begin at a few hundred dollars. However, a visual calibration tool such as Adobe Gamma or the ColorSync Default Calibrator can still provide good results, and you probably have at least one of these tools on your system already: Adobe Gamma comes at no additional cost with Photoshop, installing automatically as a control panel on the Mac and as a control panel applet under Windows. ColorSync Default Calibrator comes as part of the Mac OS: Look for the Calibrate button within the Monitors and Sounds control panel.
To use Adobe Gamma or ColorSync Default Calibrator effectively, make sure to follow these steps:
- Stabilize your ambient lighting as much as possible. Our eyes adapt to changes in ambient light, but monitors don't. If you calibrate the monitor when the rays of the setting sun are coming in through a west-facing window, it's a safe bet that colors will look very different in the cold light of morning.
- All visual calibrators use an existing profile as a starting point. You'll get much better results if that starting profile bears some reasonable resemblance to the correct profile for your monitor. If your monitor has switchable white points, you'll get a better result if the profile uses the same white point setting as the monitor. If you can't find anything better, the sRGB profile is a decent starting point for monitors with a 6500K or D65 white point.
- If you use Adobe Gamma, use the option that lets you set the individual red, green, and blue gammas rather than the Single Gamma option. It's often difficult to see any change when you're trying to match the blue square to its background, but if you set your desktop to a neutral gray, and watch what happens when you adjust the blue slider, it's a lot more obvious: Just tweak the blue slider until the gray background looks neutral.
When using Adobe Gamma, choose the option that lets you adjust individual red, blue, and red gammas.
Mac users should note that the Default Calibrator in ColorSync 3.0 often produces monitor profiles with very yellow whites, due to a bug that got fixed in ColorSync 3.0.3. Either upgrade to the newer version or use Adobe Gamma instead.
Unless you have good reasons to do otherwise, I generally recommend calibrating monitors to D65/6500K white, with a gamma of 2.2. But color management doesn't really care what standard you use, as long as it knows what that standard is by way of an accurate monitor profile.
When you "calibrate" your monitor, either by eyeball or with an instrument, you actually do two things. One is the actual calibration of the monitor, which simply means putting it into a known state, with a specified white point and gamma. The other is to create a profile that describes that known state -- a process often known as characterizing the monitor. Most so-called monitor calibration tools conflate the two processes into a single whole, but they are still really doing both things.
One implication of this is that there are two things that can go wrong during the calibration process. It's quite possible to get a good monitor calibration but a bad monitor profile. (Conceptually at least, the converse is also true, but I've never seen it happen.) If things appear normal in non-color-managed applications, but seriously out of whack in Photoshop and other color-managed apps, it's a sure bet that the monitor profile is off the mark. In Photoshop 5 or 5.5 you can check by temporarily turning off "Display Using Monitor Compensation" in the RGB Setup dialog box, but in Photoshop 6, monitor compensation is always turned on: Photoshop 6 displays everything through your monitor profile, so it better be as accurate as you can make it.
Once you've tamed your monitor, you can proceed to configuring Photoshop's color management. In older versions of Photoshop you had to visit several dialog boxes to do so, but in Photoshop 6, the basic settings are all contained in one scary-looking überdialog, Color Settings, which you can find on the Edit menu.
Photoshop 6 presents all its basic color-management settings in one Color Settings dialog.
Let's leave aside the choice of profiles for RGB, CMYK, Gray, and Spot working spaces for the time being. The really important settings are in the Color Management Policies section of the dialog. These policies control how Photoshop behaves when it encounters profiles (or fails to do so). They also dictate just how important the other choices in the dialog will be.
Photoshop lets you set one of three policies -– Off, Convert to Working RGB, and Preserve Embedded Profiles -- separately for RGB, CMYK, and Gray. Let's look at what each policy does.
Off: "Off" is really a misnomer for this policy, because you can't turn color management completely off in Photoshop 6. For one thing, Photoshop 6 always displays color through your monitor profile. For another, when you ask Photoshop to convert an image from one mode to another -- RGB to CMYK, for example -- it has to make some assumption about the colors represented by RGB and CMYK numbers so that it can convert from one to the other.
A less-misleading rubric would be "behave like Photoshop 4," but that would doubtless have been less comforting to users who have concluded that color management is so scary and confusing that they just want it to go away. If you've read thus far, we assume you aren't one of them.
Here's what the Off policy really does:
- When Photoshop encounters an image with an embedded profile that differs from the working space you set for the image's color mode (RGB, CMYK, or Gray), it discards the embedded profile and treats the image as being in the color mode's working space. This pretty much guarantees that the colors display incorrectly. When you save the image, Photoshop doesn't embed a profile, so the actual colors the numbers in the image are supposed to represent become lost.
- When Photoshop encounters an image with an embedded profile that's the same as the working space set for the image's color mode, it preserves the profile. When you save the image, Photoshop embeds the working space profile. This at least gives downstream color-savvy applications and users a clue that the numbers in the image belong to Adobe RGB (1998), for example.
Ultimately, then, if you choose Off as your policy, the role of the working space becomes paramount, because everything will be interpreted as being in that working space. Workflows do exist that would benefit from this policy, but if you're trying to get a handle on managing color with Photoshop, the Off policy is not a good place to start.
Convert to Working RGB: Unlike "Off," this policy does what it says. When Photoshop encounters an image with an embedded profile that differs from the working space profile you set for the image's color mode, it converts the image from the embedded profile's space to the working space. The numbers in the image change, but the color appearance is preserved. When you save images, the working space profile gets embedded. You can think of this option as "behave like Photoshop 5/5.5," in that each color mode has only one working space, and every image gets converted to that working space.
This policy too fits some workflows well, but again it probably isn't the best place to start when you're trying to understand exactly what's going on with color, because it makes Photoshop do things to the color automatically, without any file-specific instructions on your part.
Preserve Embedded Profiles: When you set the policy to Preserve Embedded Profiles, Photoshop keeps each image in the color space dictated by the embedded profile. The numbers in the document stay unchanged, and the colors are displayed correctly. In effect, the embedded profile space becomes the working space for that document. This "per-document" approach to color might at first glance seem like a recipe for chaos, but Photoshop offers some easy ways to keep track of each image's space, and it puts you fully in control. It also reduces the role of working spaces to one of convenience rather than necessity.
The main benefit of Preserve Embedded Profiles is that it gives you a chance to evaluate the image before you decide whether or not to make any conversions, preserving both the numbers in the document and the color appearance those numbers represent. As such, it's by far the safest choice. You can always elect to treat an image as the other policies would -- discarding the embedded profile, or converting the image to your working space -- but at least you get to see it first. So unless and until you're sure that the automatic behavior of one of the other policies will work for you, "Preserve Embedded Profiles" is the safest starting point.
With the Off policy in effect, this image appears dark and oversaturated, because the color numbers were misrepresented. The image was in ColorMatch RGB while the working space was set to Adobe RGB.
Convert to Working produces the correct appearance for the image. As the info palette shows, the RGB numbers have changed because of the conversion.
With the Preserve Embedded Profiles policy, the underlying numbers stay the same as with the Off policy, but the image is interpreted correctly as being in Colormatch RGB.
In addition to selecting policies within Color Settings, in that same dialog box you can and should configure warnings for three separate situations. The warnings not only notify you of the situations, they also let you take some remedial action. Let's take a look at these:
Profile Mismatches: Ask When Opening: This warning alerts you when an image has an embedded profile that differs from the current working space, and lets you take one of three actions:
- Use the embedded profile (instead of the working space) opens the image in the embedded profile's space. In effect, it uses the embedded profile as the working space for that image. If in doubt, this is usually the option to choose. You can always convert it to some other space after you've seen the image.
- Convert document's colors to the working space converts the image from the embedded profile's space to the working space. You might want to choose this option when you open an image from a scanner that embeds its profile correctly. Scanner spaces are generally not suitable for editing, so if the image needs work, you're typically better off converting it into a working space.
- Discard the embedded profile (don't color manage) is probably the least useful of the three. It can be a handy choice if you're dealing with a calibration target, where all you care about are the numbers in the file, or in a closed-loop CMYK workflow where you intend to edit the image, and only care about what the numbers will look like in your preferred CMYK working space.
Profile Mismatches: Ask When Pasting: This action kicks in when you try to transfer pixels between two documents in different color spaces but in the same color mode (that is, two different flavors of RGB or of CMYK, for example). In this situation, Photoshop needs to know whether you want to transfer the actual numbers (which will likely mean that the transferred pixels will change color appearance), or paste the colors that these numbers represent in the source document.
- Convert (preserve color appearance) converts the pixels being moved from the source document's space to the target document's space, preserving the color appearance.
- Don't convert (preserve color numbers) moves the pixel values with no conversion. They thus take on the appearance dictated by the target document's space. If you turn off this warning, the default behavior is that Photoshop preserves the color appearance when moving pixels between RGB documents, and preserves the color numbers when moving pixels between CMYK documents.
Missing Profiles: Ask When Opening: This option alerts you when the image you're opening doesn't contain a profile, and it offers you four choices for dealing with the omission. Since untagged files (those that don't contain profiles) are basically "mystery meat" in terms of color, there's no single correct way to deal with them unless you know something about the source. A strategy for dealing with mystery-meat files is really a topic deserving of its own future column, but for now, here are the options.
- Leave as is (don't color manage) treats the image as untagged, which means that Photoshop treats it as being the current working space. As a result, even though the numbers in the image remain unchanged, the appearance changes a little, or a lot, depending on how different the embedded profile space was from your current working space.
- Assign working RGB/CMYK/Gray produces a visually and numerically identical result to the first option, the subtle difference being that untagged images are always interpreted according to the current working space: If you change the working space, you change the appearance of untagged images. In contrast, an image that's been assigned a profile stays in that profile space even if you subsequently change the working space.
- Assign profile lets you assign any profile to the image, the only constraint being that the profile must be one for the image's color mode. Photoshop won't let you assign an RGB profile to a CMYK image, or vice versa. If you know the source of an image or can make an educated guess about it, you can use this option to assign a profile to it. For example, if your scanner software doesn't embed profiles but you have a profile for the scanner, and you know the image came from the scanner, you can assign the scanner profile here.
- Assign Profile and convert document to working RGB/CMYK/Gray lets you assign a profile, as in the previous option, and then convert the image from that profile's space to your working space. If you know the image's source, and you know that you want to convert the image to your working space for editing, this can be a useful option, but if you're in doubt it's best avoided.
The safest starting point is to set all Color Management Policies to Preserve Embedded Profiles, and to turn all warnings on. The other two policies change either the numbers in the images or the interpretation of those numbers automatically, which is great if that's something you understand and want to happen, but confusing at best and disastrous at worst when you don't. The warnings give you a moment's pause to consider the situation, and to act accordingly.
Setting the Color Management Policies as shown in the bottom half of the dialog (above) should work best for most circumstances.
Getting a Clue
When you set up Photoshop Color Settings as recommended here, your choice of working space becomes much less critical than in any other configuration, because each document can essentially have its own working space. To make per-document color more manageable, Photoshop lets you see which space is in effect for each image by choosing Document Profile from the pop-up menu at the lower left of the image window.
Photoshop also provides subtle clues when an image is either untagged or in a different space than the current working space. Each window's title bar lists the filename, the zoom percentage, and the color mode. Untagged files display a pound sign (#) after the color mode, while images that are in a space other than the working space display an asterisk (*) after the color mode.
Here is a very general set of guidelines for using color management with the policy settings we've recommended:
- First, evaluate the image by opening it in its embedded profile's space. If it looks good and doesn't require much editing, convert it to your output space with Convert to Profile (from the Mode submenu of the Image menu). Particularly if the image is in an RGB capture space -- the color space of a scanner or digital camera -- convert it into a working space before doing any heavy editing, using Convert to Profile. This is a good idea because RGB capture spaces are rarely gray-balanced or uniform, and RGB printer spaces are even less so, making it hard to edit in them.
- If an RGB image is in a working space that's different from the one you use, it's probably better to leave it in that space for editing rather than converting it to your working space: Repeated color space conversions will degrade the image, so unnecessary ones are best avoided. That said, if you plan to composite the image with others that are in your working space, go ahead and convert it, because you'll have to do so for compositing anyway.
- Even if you know the CMYK printing process for which an image is destined, it still makes sense to make a quick evaluation of the image in its embedded profile space. Doing so allows you to get an idea of the intentions of those who created the file. By embedding the profile, they are essentially telling you how they want the image to look. Then, you can determine how the file will actually print on your printing process either by assigning it your CMYK profile using Assign Profile from the Mode submenu, or, if you've set the profile for that printing process as your CMYK working space, by choosing Proof Colors from the View menu. Depending on how the image looks, you may want to convert it from the embedded profile to your CMYK profile, or simply edit the image to the desired appearance. In the latter case, use Assign Profile to assign your CMYK profile.
Soft-Proofing and Printing
So far we've covered all the basics except how to soft-proof and print your color-managed images. These topics demand a column of their own, however, partly because of the platform differences between the Mac and PC. We'll tell you what you need to know in part 2 of this article, in an upcoming Out of Gamut. In the meantime, my past column on soft-proofing in Photoshop 6.0 may give you a head start.
Read more by Bruce Fraser.
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