Checking for Out-of-Gamut Colors

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Checking for Out-of- Gamut Colors

One of the key reasons why color often does not match between devices is that it may be out-of-gamut for the device it's being reproduced on. In other words, the device simply cannot reproduce that color.

Note

For more on rendering intents, see Chapter 1.

If you are soft proofing an image that contains out-of-gamut colors, the soft proof on your screen will be displayed with gamut mapping, meaning that the out-of-gamut color will be displayed as the next - closest reproducible color (hence the reason it looks different when soft proofed on the screen). Gamut mapping brings out-of-gamut colors into gamut. The rendering intent determines which in-gamut color is selected to replace the out-of-gamut color. If the colors are only slightly out of gamut, the effect may be subtle. In any case, it's often useful—even important—to know which colors are out of gamut.

Using Photoshop's Gamut Warning Feature

Luckily, Photoshop offers a feature called the Gamut Warning, which lets you see whether any of the colors in an image will be out of gamut for your selected printing device. Gamut Warning uses the settings in Customize Proof Condition dialog box to determine the target output device, and then it compares the colors in the image to the gamut of the profiled device. It displays any out-of-gamut colors in gray. Gamut Warning is a useful feature in conjunction with soft proofing.

Open the Tulips.jpg image in Photoshop and ensure that your Custom Proof setup from the previous exercise is chosen . You can toggle Proof Colors on and off to simulate the output of the device that you selected in the previous exercise.

Choose View > Gamut Warning.

Figure 6.12.

Photoshop displays the image with the out-of-gamut colors in gray.

Figure 6.13.

The areas shaded in gray are colors that cannot be reproduced by the output device denoted by the selected profile in the Customize Proof Condition dialog box.

Tip

You can perform additional color corrections with Gamut Warning enabled to further optimize your image, based on the gamut limitations of the selected device.

Toggle Gamut Warning on and off by pressing Shift-Control-Y to see the affected colors.

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Applying Color Management During Printing

The most confusing part of color management is often printing, as there are many options in various locations. Photoshop provides a centralized location to apply color management to images during printing, which provides the following advantages:

You can easily send one image to multiple devices, and even generate separations for press output, with as close a match as possible between the devices.
Photoshop supports both RGB and CMYK workflows.
An image printed from Photoshop will match the onscreen soft proof or device proof as closely as possible.

Using Photoshop's Proofing Feature

The key to successfully printing with color management is to ensure that color management is applied only once. This means disabling any color management features in the printer driver and operating system to ensure that Photoshop is the only place that color management is being applied.

In Photoshop, make sure that the Tulips.jpg image is still open .

Choose File > Page Setup.

Confirm that Paper Size is set to Letter (or A4 if you're outside the United States), and that Orientation is set to Landscape.

Figure 6.14.

Click OK.

Choose File > Print with Preview.

In the Print dialog box that appears, click the More Options button if it is not already selected.

Figure 6.15.

Select Color Management from the Color Management drop-down menu, located on the left side of the dialog box.

Tip

The Print and Print with Preview dialog boxes in Photoshop 7 and CS are slightly different than in Photoshop CS2. (We're using CS2 in these exercises.) For instructions on setting up these versions, see the appendix.

Figure 6.16.

In the Print section, confirm that the Document radio button is selected.

This tells Photoshop to use the working space as the source space, which in the case of the Tulips.jpg image is Adobe RGB (1998).

Note

The Proof option is used to perform device simulation on the output device. This feature is covered in more detail in Chapter 9.

Figure 6.17.

In the Options section, for Color Handling, choose Let Photoshop Determine Colors, and from the Printer Profile drop-down menu, choose the profile for your printer.

This tells Photoshop to color manage the file from the working space to that of the printer profile.

Note

Color is subjective . If you find that the Relative Colorimetric intent does not produce a good screen-to-print match for your particular images, choose a different rendering intent, such as Perceptual.

10.

From the Intent drop-down menu, select Relative Colorimetric. Make sure the Black Point Compensation option is selected.

Figure 6.18.

11.

Click Print. In the Print dialog box that appears, choose your printer from the Name drop-down menu.

Figure 6.19.

12.

Click the Properties button to locate your printer's properties, and then choose the correct paper for your device. Be sure to select the same resolution (and any other related settings) that you used when you created the profile.

The following figure shows the Epson Stylus Photo 2200 Properties dialog box, with Premium Luster Photo Paper chosen from the paper type drop-down menu in the Paper & Quality Options section.

Figure 6.20.

13.

Locate your printer's color management options and turn them off. The location of these options varies with each printer; look for them in the printer driver dialog box under a heading such as Custom, Advanced, or Color Management.

Figure 6.21 shows the Color Management options in the Epson Stylus Photo 2200 Properties dialog box, with No Color Adjustment selected.

Figure 6.21.

14.

Click OK to close the Properties dialog box and then click Print in the Print dialog box to start printing.

Tip

Save these settings to use when printing with the profile again by choosing Save Setting in the Properties dialog box. It's important to always print with the same settings—changing the resolution or paper type will affect the results.

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