Chapter 15: Working with Color

Color is a complex subject, and this chapter will help you work successfully with it. You’ll manage color workflows, starting with input from digital cameras to display on your computer monitor, then representation in Photoshop, and ultimately output made by printers. Sometimes the pictures you take will have color casts. You’ll learn how to use curves to correct color and employ various adjustments to alter color for artistic effect. Finally, you’ll soft proof color onscreen to get a sense of how it will look prior to professional CMYK printing.

Managing Color

Without color management, it is very likely that the color you see on your camera’s LCD will be different from both the color on your computer monitor and the color of printed output. The reason we need color management is because every device handles color a bit differently. Recall from Chapter 3, “Digital Imaging Fundamentals,” how color is stored in grayscale channels. Color is therefore something that must always be interpreted. The absolute color is never actually recorded, only intensities in three different wavelengths of light corresponding to the red, green, and blue primaries.

The range of visible light is called the full color gamut. Computers cannot display, and printers cannot print, the full dynamic range or color gamut that our eyes perceive. Instead, various color spaces have been standardized to represent the most common colors. Figure 15-1 shows the full gamut outlined in the graph and the Adobe 1998 color space defined within the triangle. Daylight standard D65 is also indicated.

Adobe published the color space that bears its name in 1998 in an effort to encompass most of the colors that professional CMYK printers are able to output.

Figure 15-2 shows the sRGB color space, which has a narrower gamut than the Adobe RGB 1998 color space.

The sRGB (standard RGB) color space is the de facto standard on the Web. If a camera doesn’t support color profiles, or if an image lacks a color profile, or if the browser doesn’t support color profiles, one can assume that the image will be in the sRGB space. Think of sRGB as the lowest common denominator and narrowest of color spaces.

Both Adobe RGB 1998 and sRGB were designed to be viewed under D65 lights. D65 lights have a color temperature of 6500 degrees above absolute zero, which most closely simulates the light of the sun through Earth’s atmosphere. If you don’t use D65 daylight bulbs in your environment, then the colors you see will be shifted from these standards.

There are many other color spaces in addition to Adobe RGB 1998 and sRGB; ColorMatch and ProPhoto are two popular examples. Figure 15-3 shows the subtle differences in viewing the same data in different color spaces.

Both Mac OS X and Windows 7 manage color at the operating system level. Printer drivers also try to manage color at the level of hardware. These layers of management occur on top of the color management that Photoshop automatically performs. If you set up Photoshop to use sRGB, the colors will shift again at the operating system level before being displayed on your screen, so what you see onscreen won’t actually be in sRGB.

Configuring Color Settings

If you are creating graphics for the Web or mobile devices, the best solution I have found is to disable color management in Photoshop. If, on the other hand, you are creating graphics for print, you should use Photoshop’s color management system with your chosen working color space. In the following steps you will specify color settings for both situations and then synchronize all your color settings across the applications in the Creative Suite (if you own more Adobe applications in addition to Photoshop).

1. The first step is to create a color profile. How you do this depends on what equipment you have and what computer operating system you use. If you own a colorimeter or a (more expensive) spectrophotometer, you can measure the light emitted from your monitor and use the software included with your device to create an accurate color profile of your monitor. If not, you can use the color profile or color calibration utilities that come with your operating system to “eyeball” a profile. (Keep in mind that this is far less accurate than using a meter.)

Save a profile with the name of your computer followed by the word Calibrated (i.e., iMac Calibrated).

2. Launch Photoshop and choose Edit ⇒ Color Settings. Select the profile you just created for the RGB working space in the previous step. I chose Monitor RGB—iMac Calibrated because I produce web graphics rather than images printed on a desktop printer. If you produce printed matter on a desktop printer, you might choose Adobe RGB (1998) or the color space of your choice. Figure 15-5 shows the Color Settings dialog box.

3. Contact the professional printing company you use for offset printing and select the CMYK working space they specify. For example, you might select U.S. Sheetfed Coated v2. Select Gray Gamma 2.2 if you are using any version of Windows or Mac OS 10.6 (Snow Leopard) or later. Select Dot Gain 20% or whatever your professional printing company specifies for spot color.

4. Select a color management policy:

Select Off as your RGB color management policy if you intend to create output for the Web.
Select Preserve Embedded Profile to leave existing profiles alone.
Select Convert To Working RGB if you want Photoshop to convert to your chosen print color space.

I select Convert To Working CMYK and Convert To Working Gray if I ever open documents in CMYK or Grayscale color modes.

5. Select whether you want to be informed of profile mismatches and/or missing profiles.

I prefer not to be queried every time I open an image. so I deselect the Missing Profiles check box.

6. Click Save, type My Color Settings.csf, and click Save. Figure 15-6 shows the resulting settings, which are now saved as a preset. Click OK to close the Color Settings dialog box.

7. Select File ⇒ Browse In Bridge. In Bridge, select Edit ⇒Creative Suite Color Settings. Select My Color Settings and click Apply (see Figure 15-7).

8. Close Bridge and switch back to Photoshop.

9. Choose Edit ⇒ Color Settings. The top of the dialog box shows that your chosen settings are synchronized across the Creative Suite (see Figure 15-8).

Assigning and Converting Color Profiles

There is an important difference between assigning color profiles and converting color profiles. Assigning profiles is nondestructive, meaning it does not change the underlying pixel data. Different profiles affect only the delivery of that information to the screen. On the other hand, converting profiles alters the pixel data while keeping the colors as close as possible to how they are represented in the current profile. In the following steps you will both assign and convert profiles.

1. Open Leaves.jpg from the book’s Download page at www.sybex.com/go/photoshopessentials. Depending on what you chose in step 5 in the previous section, you might be asked what to do because of the mismatch between the embedded and working profiles (see Figure 15-9). Assuming you want to use this image for Web output, select Discard The Embedded Profile (Don’t Color Manage) and click OK. The document now lacks a color profile.

2. To view the image correctly in Photoshop, you should assign your monitor’s calibrated profile to the image. Select Edit ⇒ Assign Profile. Select Working RGB, which was set to iMac Calibrated (or whatever you named your color profile in step 1 of the previous section, “Configuring Color Settings”). See Figure 15-10.

3. Suppose you decided to prepare this image for professional printing on a four-color printing press. Choose Edit ⇒ Convert Profile. The destination space is set to the profile you set up as your working CMYK space in the previous section (U.S. Sheetfed Coated v2 in the example shown in Figure 15-11). Click OK.

4. The title bar now says CMYK/8, meaning you now have a four-channel document with 8 bits per channel. Select the right-facing arrow at the bottom of the document window and select Document Profile from the menu that appears. The color profile is now shown at a glance (see Figure 15-12).

5. Close the document without saving.

Correcting Color

When you take photos under artificial lighting, they can be left with a noticeable color cast that can negatively influence the feeling. In other cases, natural light might appear too warm or too cool for your taste and you might want to intentionally create a color cast to shift the subtle balance of color.

Using Curves to Set Black, Gray, and White Points

In the following steps you will remove an undesirable yellow color cast using the Threshold and Curves adjustments.

1. Open Man.jpg (see Figure 15-13). This image has a yellow cast from the artificial lighting.

2. Press Cmd+J to duplicate the Background layer so you can make a before-and-after comparison onscreen.

3. Choose Layer ⇒ New Adjustment Layer ⇒ Threshold to help you identify the black, gray, and white points on the image. Click OK when prompted to name the layer Threshold 1. Drag the slider in the Properties panel all the way to the left and then slowly drag it to the right until you start to see some black in the document window (see Figure 15-14). The first places you see black are the darkest pixels in the image.

4. Select the Color Sampler tool. Click one point inside the darkest part of the image as indicated by the Threshold adjustment layer to place marker #1.

5. Drag the Threshold slider in the Properties panel all the way to the right. Then back the slider off slightly to the left until you see some white appear in the document window; this represents the brightest part of the image. Click inside the white area to place color sampler marker #2.

6. Drag the Threshold slider to the left and observe which pixels change color from black to white near the middle of the histogram. Click once more in the document window (in this case in the lower-right corner) to set marker #3. Figure 15-15 shows the location of the three markers.

Figure 15-15: Placing color sampler markers at the brightest and darkest parts of the image and midpoint as indicated by the Threshold adjustment

7. Press Delete to get rid of the Threshold 1 layer because it is no longer needed.

8. Choose Image ⇒ Adjustments ⇒ Curves. Select the Sample In Image To Set Black Point tool in the Curves dialog box and click sampler marker #1 in the document window. Select the Sample In Image To Set White Point tool and click sampler marker #2. Select the Sample In Image To Set Gray Point tool and click color sampler marker #3 (see Figure 15-16).

9. Click the Clear button on the options bar to remove the color sampler markers. Figure 15-17 shows the result.

10. Save your work as Man-color-corrected.psd. Toggle Layer 1 off and on to see before-and-after views.

Use the Eye Dropper tool and press the Shift key to determine exact RGB and CMYK values of specific areas of the image. The color values can be viewed in the Info panel and used as a guide for correction.

Creating a Color Cast with the Photo Filter

Photo Filter is not a filter but an adjustment (and adjustment layer) that allows you to introduce a digital color cast, which works much like a color filter screwed onto a physical lens. In the following steps you will cool a hot summer day with a blue photo filter in Photoshop.

1. Open Landscape.jpg (see Figure 15-18). This image has a yellow cast from haze in the warm air.

2. Choose Layer ⇒ New Adjustment Layer ⇒ Photo Filter. Experiment by selecting different filters from the Filter drop-down in the Properties panel. I like Cooling Filter (80), but the choice is very subjective (see Figure 15-19).

3. Save your work as Landscape-with-photo-filter.psd. Figure 15-20 shows the result. Toggle the Photo Filter 1 layer off and on to see before-and-after views.

Adjusting Color

You have complete control over color in Photoshop. If you don’t like how a color looks, adjust it! You are limited only by your creativity and your skill with selection (covered in Chapter 7, “Selecting Pixels”). In the following steps you will draw attention to a model by desaturating the color of the background. Then you will adjust the color of her coat. These are just two examples of what you can do with color and adjustment layers.

1. Open Woman.psd (see Figure 15-21).

2. Choose the Quick Select tool and select Auto-Enhance on the options bar if it is not already selected. Drag over the woman to select her. Hold down Opt and drag over anything selected that is not part of her body or clothing.

3. Press Shift+Cmd+I to select the inverse (everything but the woman).

4. Click the Black & White icon in the Create panel. The current selection automatically becomes a layer mask on a Black & White adjustment layer. Drag the Reds slider to -110 and the Yellows slider to +166 (see Figure 15-22).

5. Select the woman’s white coat with Quick Select. Again, hold down Opt and remove any areas you unintentionally select. Use any of the selection techniques you learned in Chapter 7 to refine the selection so that only her coat is selected and not her hands, face, or hair (see Figure 15-23).

6. Click the Hue/Saturation icon in the Create panel. In the Properties panel, select Colorize. Drag the Saturation slider to 51 and the Lightness slider to -62. If you wanted to change the hue, it would be as simple as dragging the Hue slider, but in this case I like red (see Figure 15-24).

7. Save your work as Woman-adjusted.psd. Figure 15-25 shows the result.

Proofing Color

Before you print a hard proof on paper, it is always a good idea to view a soft proof onscreen because you can save valuable paper and ink this way. Most printer manufacturers offer International Color Consortium (ICC) files for output created with specific combinations of specialty papers, printers, and driver software. I recommend that you search your printer manufacturer’s website and download not only the drivers but any ICC files they offer (the filename extension is .icc). In the following steps you will download specific ICC files, set up a custom soft proof, and then color-correct the print prior to creating a hard proof. (Hard proofs, also known as printed output, are covered in Chapter 16, “Creating Output.”)

1. Download the premium glossy ICC profiles for the Epson Stylus Photo 2200 printer, which as of this book’s publication date are here:

If these are not available, search for the ICC files for your own printer and paper.

2. Install these drivers according to the manufacturer’s instructions. Mac ICC files go in /Library/ColorSync/Profiles, and Windows ICC files go in C:\Windows\system32\spool\drivers\color.

3. Open Rowboat.jpg. If asked, choose Use The Embedded Profile (sRGB).

4. Choose Image ⇒ Duplicate. Accept the default name Rowboat copy and click OK in the Duplicate Image dialog box. Choose Window ⇒ Arrange ⇒ 2-Up Vertical.

5. In Rowboat copy, choose View ⇒ Proof Setup ⇒ Custom. Select SP2200 Prem.Glossy 2880.icc from the Device To Simulate drop-down. Deseselect Preserve RGB Numbers and select Perceptual from the Rendering Intent drop-down. Select Black Point Compensation and Simulate Paper Color (see Figure 15-26). Click OK. The colors in Rowboat copy now look as close as they can on-screen to how they will look when printed by the specific device on the specific paper.

Rowboat copy looks different from the original appearance of the image in Photoshop. If you want to maintain the original look in the print, you can perform some color adjustment to try to make the soft-proofed Rowboat copy more closely match Rowboat onscreen.

6. The soft proof version looks washed out compared to the original. To compensate, select the Brightness/Contrast icon in the Create panel. In the Properties panel, drag the Brightness slider to 11 and Contrast to 26.

7. The water in the soft proof still doesn’t look anywhere near as dark as in the original. Select the Selective Color icon in the Create panel. In the Properties panel, select Green from the Color drop-down (to affect the water). Drag the Black slider all the way to +100% (see Figure 15-27).

8. Save your work as Rowboat-soft-proofed.psd. Figure 15-28 shows the side-by-side comparison. The adjusted image will now print close to how the original appears onscreen.

The Essentials and Beyond

In this chapter you learned how to work with color, including assigning and converting profiles to management workflows, correcting color casts with curves, shifting color with adjustments, and finally, soft-proofing color prior to committing to output.

Additional Exercise

Go outside and take some pictures. After you review, develop, and retouch the best photo from the shoot, soft-proof the photo onscreen. Finally, shift its color using any of the following adjustments to make it stand out: Brightness/Contrast, Curves, Vibrance, Hue/Saturation/Color Balance, Photo Filter, and/or Selective Color.

Image courtesy Richard Trueman