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by John Dudak
Someday, the colors you see on your monitor will be the same as the colors I see on mine--regardless of manufacturer, platform, or Web browser. And, eventually, when you print a file to your desktop printer, take it to a photo lab, or send it to an offset printer, you’ll get the product you wanted back without undue difficulties along the way. The International Color Consortium (ICC) made this predictability possible by establishing standards for color that all venders have agreed to meet. But Adobe opened the proverbial can of worms with Photoshop 5.0’s innovative color management options, which take full advantage of those standards and the necessary ICC profiles that convey color information from one device to another.
Device-independent color spaces and a Reference Color Space (RCS) are at the core of universal color management. A device-independent color space uses predetermined parameters for white point, gamma, and the RGB color primaries. The ICC chose the Commission Internationale de l'Eclairage (CIE) Color Model as the reference color space. It’s based on human perception rather than on absolute color. Once a color is defined by the RCS, it can be accurately reproduced in any color space.
In Photoshop 5.0’s new color management system, you no longer edit your images in your monitor’s color space, which is device-dependent. Instead, you edit in one of the device-independent color spaces. The colors are passed on to the RCS, and the Adobe Color Matching Method (CMM) tells your monitor how to display them properly. Your file is saved with an embedded ICC profile that describes the color space; and when it’s opened on a different computer and monitor, Photoshop reads the profile and uses the CMM and RCS to display the image accurately.
In all previous versions of Photoshop, the monitor’s color space was the editing space. Therefore, unless two monitors were identical, they would display an image differently. The problem wasn't restricted to differing brands, either. Monitors change color as they age, so even identical models can display colors differently, depending on the amount of use each has had.
Success with Photoshop 5 and color management in general depends on two things--calibrated monitors and accurate ICC profiles. The profiles Photoshop embeds are accurate. They are also fairly simple as they describe a color space. Generic device profiles, however, are another matter. If you've ever tried to print to an ink-jet printer using the Apple ColorSync or Microsoft ICM option, your less-than-stellar results were probably due to the generic device profile--that is, if you were working with a calibrated monitor. If not, then that’s your first step to successful color management.
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| Click the Load button, and load the profile you got from your manufacturer’s Web site. |
Hardware calibration will provide the most precise results. But hardware calibration equipment, along with the necessary software, requires another investment, and you already have an effective calibration device within Photoshop 5--Adobe Gamma. Just follow the directions in the Assistant (Mac) or Wizard (Windows) dialog boxes. (Be sure to leave your monitor turned on for an hour before you calibrate. It can take that long for the colors to stabilize.)
All Mac--but not all Windows--systems can be calibrated with Adobe Gamma. It is, however, worth using even for those Windows systems that can’t be calibrated, because it'll place a profile in the proper place in the registry for Photoshop and ICM to use as the monitor profile. Otherwise, Photoshop is just using a generic RGB profile that may or may not match your monitor.
In all cases, you should start by downloading your monitor’s generic profile from the manufacturer’s Web site. For example, I have a Sony seventeen-inch monitor, and I found three Sony profiles for my monitor--one for 5000K, one for 6500K, and one for 9300K. If you're given the same selection, choose the one for 6500K. It represents the monitor’s white point and will provide the most neutral whites for the majority of users. If your monitor has a color control option, set that to 6500K, as well.
On a Mac, place this profile in the "System Folder/ColorSync Profiles" folder for ColorSync 2.5 or above or "System Folder/Preferences/Colorsync Profiles" folder for older versions. On Windows 95/98, place this in the "Windows/System/Color" directory. On Windows NT, place this in the "WinNT/System 32/Color" directory. This folder/directory is where you'll save all of your profiles.
When the Assistant/Wizard shows you the currently loaded profile, click on the "Load" button and choose the profile you received from the manufacturer’s Web site. Now, even if you can’t use the gamma controls in the Wizard, you’ll at least have loaded a profile that’s in the ballpark of your monitor’s colors. (Note: Mac users, be sure to start with the generic profile and not one you created with ColorSync.)
When your monitor is calibrated, select the RGB color space in which you want to work. Adobe provides nine built-in profiles for device-independent RGB. Only two, however, are useful as general-purpose editing spaces--ColorMatch RGB and Adobe RGB (1998). They have fairly wide gamuts, which means they encompass a broad range of colors, and they work well for converting to CMYK, printing to RGB devices, and preparing images for the Web.
The ColorMatch RGB space is based on the Radius PressView monitor, which is popular for pre-press work. It has a gamma of 1.8 and a white point of 5000K (D50). The Adobe RGB (1998) space has an even wider color gamut, a gamma of 2.2 and a white point of 6500K (D65). Of the two, I prefer the Adobe RGB (1998). I believe I get better detail in the darker tones with the 2.2 gamma, and I've never been able to use a monitor with a D50 white point. The whites always look too yellow to me. However, I don’t use the Adobe RGB (1998) space. I use the variation of it suggested by Bruce Fraser, the co-author of Real World Photoshop 5. The Bruce RGB space is identical to the Adobe RGB (1998) space except for the green primaries. They don’t extend as far into the green area of the spectrum. Bruce provides excellent reasons for using his space in the book. I've been using the space for several months for print and Web work with superb results. (You can download an excerpt from his Web site at www.pixelboys.com.)
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| In the "RGB Setup" dialog box, the monitor profile you created using Adobe Gamma should show next to "Monitor," and be sure to keep "Display Using Monitor Compensation" checked. |
You'll find the "RGB Setup" dialog box under "File/Color Settings/RGB Setup." Choose the RGB space you want to use. The "Monitor or Simplified Monitor" option would set your monitor as the color space, which is not what you want unless you prepare images only for the Web. Even then, you'll get better results by working in one of the three spaces indicated above and later converting for the Web. The profile you created using Abobe Gamma should show next to Monitor. And be sure that the "Display Using Monitor Compensation" box is checked. It tells Photoshop to display the image in the chosen space and engages the RCS to make the necessary on-the-fly conversion so it displays accurately.
Choose "Custom" if you want to use Bruce RGB as your working space. Type BruceRGB, set the Gamma to 2.2 and choose 6500K (D65) as the "White Point." Select "Custom" as the "Primaries" and enter Red x = 0.6400 y = 0.3300, Green x = 0.2800 y = 0.6500, Blue x = 0.1500 y = 0.0600. Click the "Save" button, and save the profile with your others.
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| The same profile set in the Built-in CMYK Model, saved as an ICC profile in the Tables option, and then loaded in the ICC option. |
The CMYK Setup comes next. You have three choices next to "CMYK Model"--"Built-in," "ICC," and "Tables." "Built-in" provides the same controls in one dialog box that Photoshop 4 provided in two. "Dot Gain" delivers slightly different results, though. For example, I used a dot gain of thirty-two percent for SWOP (Newsprint) with Photoshop 4 and now get the same results using thirty percent with Photoshop 5. Check with your printer to get the right settings. Use the "ICC" option if your printer gives you an ICC profile. Choose the "Built-in Engine," "Perceptual (Images) Intent," and keep the "Black Point Compensation" box checked, unless you have a good reason to do otherwise. The "Tables" option allows you to load custom separation tables created and saved in Photoshop 4.
The "Tables" option also allows you to save an ICC profile of the currently loaded settings, and it automatically loads the last settings used before switching to Tables. Therefore, you can set up your CMYK Model using the "Built-in" option according to your printer's recommendations and then switch to "Tables" to save those settings as an ICC profile. If you do, though, you should set your dot gain as a curve in the "Built-in" option, even if you're using a Standard Dot Gain percentage. You make the Standard Dot Gain a curve simply by setting the "Standard Dot Gain" percentage and then switching to "Curves." You would be able to use that profile in ICC-aware applications such as QuarkXpress 4 or PageMaker 6.5. And you can even load it in the ICC model in Photoshop. However, you do have to shut down and re-open Photoshop before it recognizes the profile.
Fortunately, ICC profiles can be used on any platform. So, if your printer creates a profile on a Mac using the Tables feature, you'd be able to use it on a Windows machine simply by typing .icm at the end of the profile.
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| Grayscale Setup with "Black Ink" checked so the image displays the dot gain set in the CMYK Model. |
The Grayscale Setup is fairly simple. Use "RGB," if your images are for the Web. Use "Black Ink," if your images will be printed. When "Black Ink" is checked, the dot gain percentage in the "CMYK Setup" dialog box is used when displaying the image.
Profile Setup comes next. The "Profile Setup" dialog box tells Photoshop whether or not to embed profiles and what to do when images without profiles or with profiles that don’t match your current RGB, CMYK, or Grayscale Setups are opened.
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| The image at left shows the image as it appears on the Web when saved with the profile embedded but viewed on a browser that can’t read profiles. The picture in the middle shows the image as it should appear. It was converted from the BruceRGB space into the monitor space and saved without embedding a profile. The image on the right shows how the image in the middle appears in the BruceRGB space with "Display Using Monitor Compensation" turned on. |
Most of the time, you'll want to embed a profile in the image. A checkmark next to the color space in the "Embed Profiles" section tells Photoshop to embed the profile for the color space you've chosen in the RGB, CMYK, and Grayscale Setup dialog boxes. Right now, however, not all devices can read ICC profiles. Specifically, most Web browsers don’t read them. Therefore, they display your image just as Photoshop does when you turn off the "Display Using Monitor Compensation" option in the "RGB Setup" dialog box.
You can work around this and still edit your Web images in one of the device-independent spaces, through the use of the "Profile-to-Profile" command. When you're finished editing the image, make a copy and save the original. With the copy still open, select the "Profile-to-Profile" command, which is under "Image/Mode/Profile-to-Profile." Choose your editing space for "From." Choose the profile you created with Adobe Gamma for "To." Use the "Built-in Engine, Perceptual Intent," and keep "Black Point Compensation" checked. Click "OK" to make the conversion. Then, open the "Profile Setup" dialog box and uncheck "RGB" in the "Embed Profiles" section, and save the image with your chosen compression. (The easiest way to do this regularly is to set up a Photoshop action. Be sure to have the action re-check RGB in the "Embed Profiles" section of the Profile Setup.)
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| Profile to Profile. To prepare your image for the Web when it was created in a device-independent color space, use the "profile-to-profile" command to convert the device-independent space ("From") into your monitor’s color space ("To"). Then save the image without embedding a profile. |
The image will look different when you open it in your working space with "Display Using Monitor Compensation" turned on, but it will appear on the Web as it does when you turn off "Display Using Monitor Compensation."
On the printing side, if you're experiencing extremely long printing times when printing your Photoshop CMYK separations or grayscale images out of your page-layout application, try them without a profile embedded. It may solve the problem. One problem this action produces, though, is that whenever you save an image without embedding a profile in Photoshop 5, it can be opened into a different color space without any warning that it's not the same space. (This won't be a problem between you and your printer, but be sure to embed a profile in any image you send out for general distribution.)
The "Assumed Profiles" section tells Photoshop what profile you want to choose, if the image you're opening doesn’t have a profile embedded. In other words, you're guessing. I recommend that you choose your monitor’s profile for RGB. It'll give you the best results most of the time. Choose "Ask When Opening" for CMYK. Choose "Grayscale - Gamma 1.8," if you're using a Mac; or "Grayscale Gamma 2.2," if you're using Windows. If you work with images from both platforms, choose "Ask When Opening."
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| Profile Mismatch. The "From" profile belongs to the image you're opening. The "To" profile is always your CMYK color space. |
The "Profile Mismatch Handling" section tells Photoshop what to do when you open an image with a profile embedded that doesn’t match the profile you chose in the RGB, CMYK, and Grayscale Setups. Choose "Convert to RGB Color" for RGB. Choose "Ask When Opening" for CMYK. And choose "Convert to Grayscale" for Grayscale.
With the above settings, every RGB image you open will be converted to your RGB working space. If the image has a profile embedded, it'll be used as the source profile to make the conversion. If it doesn’t have a profile embedded, your monitor space will be used as the source profile. If you open an image that looks terrible, close it without saving, change your "RGB Assumed Profile" to "Ask When Opening" and re-open the image. You should get a "Missing Profile" dialog box. Choose a profile other than your monitor profile as the "From" profile and click "OK" to see how that looks. "ColorMatch RGB" or "sRGB" are likely choices. Most of the time, though, if your monitor profile doesn’t produce good results, the others won’t, either. Images from consumer digital cameras and inexpensive flatbed scanners can look bad no matter how you open them. You’ll just have to fix them in Photoshop.
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| Missing Profile. The "From" profile here is a guess. The "To" profile is your CMYK color space. Try it, but close the image without saving and try another if it doesn’t look good. |
With the above settings, every CMYK image you open will present you with a "Missing Profile" or "Profile Mismatch" dialog box, unless it has your CMYK Setup profile embedded or it was saved in Photoshop 5 with no profile embedded. For a Profile Mismatch, you can convert to your CMYK space, if necessary. But this works best if you're converting from a larger to a smaller gamut. For example, converting from SWOP (Coated) to SWOP (Newsprint) works. You can try converting the other way, but you may get better results if you convert to your RGB space first, fix the image as best you can, and then convert to CMYK.
If you don’t already have familiar CMYK ICC profiles in your profiles folder to use with the "Missing Profile" dialog box, you should create three profiles using the "Tables" save feature in the "CMYK Setup" dialog box. Start by choosing the "Built-in CMYK Model." Select the "SWOP (Coated)" profile, leave the Dot Gain at "Standard and 20%," select "GCR" for the Separation Type, "Light" for the Black Generation, "100" for the Black Ink Limit, "300" for the Total Ink Limit, and "0" for the UCA amount. Then, switch to the "Tables" model and save this profile to your profiles folder, using the information in the "To CMYK Table" section as the name. It should show the profile you chose in the "Built-in Model."
Do the same for SWOP (Uncoated), using "Standard and 25%" for the Dot Gain and the same Separation Options you used for the SWOP (Coated) profile. And do the same for SWOP (Newsprint), using "Standard and 30%" for the Dot Gain, "Medium" for the Black Generation, "100" for the Black Ink Limit, "275" for the Total Ink Limit, and "0" for the UCA Amount. (If you use SWOP parameters in the CMYK Built-in Model that are different from those I suggested above, by all means make profiles of them, as well. Just remember to switch your Standard Dot Gain to Curves if you want to use it in the ICC option.)
(Note: SWOP ink colors are standards for the United States. If you're working in another country, you should create three similar profiles using the default settings and standard ink colors for that country.)
When you get a "Missing Profile" dialog box, you have to choose a "From" profile if you want to view the image’s color and contrast. Choosing "None (Don’t Convert)" will open the image without changing its CMYK values, but they may not display properly. If you have a profile that you know is similar to the separation parameters used to create the file, then choose that. Otherwise, try your own profile or the three SWOP profiles you created. Simply close the image without saving to try the next one.
For grayscale images, either the "Missing Profile" dialog box will show when a profile is missing, or the image will be converted to your grayscale space when it's opened, depending on how you set the "Grayscale Assumed Profile." If the "Missing Profile" dialog box appears, try the two choices--"gamma 1.8" or "gamma 2.2." One of them will definitely look better than the other.
You may want to set all of your "Assumed Profiles" and "Profile Mismatch Handling" options to "Ask When Opening" until you feel confident about the changes being made. You'll get a good feel for what’s happening, and you may find that you prefer a different workflow than the one I suggested. It’s also a good idea to make a copy of any file that you can’t easily replace before you make any conversions. You’ll have a backup in case you permanently alter a file in a way you hadn’t intended.
The changes you make to a file using the "Missing Profile" or "Profile Mismatch" command are virtually loss-less when you stay in the same color space--for example, when converting from one RGB space to another, especially when moving from a larger gamut to a smaller one. Converting from CMYK to RGB does more harm, but you may have no choice if you're trying to make a newsprint CMYK image print to a sheet-fed press on coated paper. In any case, though, changes to the image do take place every time you make a conversion, so don’t keep jumping from one editing space to another and changing all your images each time. You'll only degrade them. And it’s always better to start from the original RGB file to make new CMYK separations rather than converting the old CMYK file to a new CMYK space. For that matter, CMYK to CMYK conversions are less user-friendly than RGB-to-RGB or Grayscale-to-Grayscale conversions. Don’t do it unless you have to.
In a fully color managed environment, your image travels from one device to another with accurate color information being relayed through ICC profiles. A source-and-destination (or "from" and "to") choice is made all along the way. It starts at the scanner or digital camera, goes to your chosen color space, and on to your output device. Your monitor provides an accurate preview, your desktop printer an accurate proof, and your press an accurate print run, because each one has an accurate ICC profile describing its color space, which allows the CMM to successfully interpret your image’s color content. Of course, we're not all there, yet. But, thanks to the International Color Consortium and Adobe’s initiative with Photoshop 5, it won’t be long.
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