Setting target colors for highlights, neutral grays, and shadows

In addition to setting the tonal range, you can use Levels to set target colors for the lightest and darkest areas of detail in the image, as well as areas of neutral gray.

When identifying the lightest and darkest areas of an image, it's important to identify representative highlights and shadows. Otherwise, the tonal range may be expanded unnecessarily to include extreme pixel values that don't give the image detail. A highlight area must be a printable highlight, not specular white. Specular white has no detail, and so no ink is printed on the paper. For example, a spot of glare is specular white, not a printable highlight.

To set target colors for highlights, neutral grays, and shadows:

1. Select the eyedropper tool, and choose 3 by 3 Average from the Sample Size menu in the eyedropper tool options. This ensures a representative sample of an area rather than the value of a single screen pixel.
2. Choose View > Actual Pixels to make sure you view the true color and tonal values of your image as you make adjustments to it.
3. Do one of the following:
• Choose Enhance > Adjust Brightness/Contrast > Levels.
• Create a new Levels adjustment layer, or open an existing Levels adjustment layer. (See Using adjustment and fill layers.)

When you open the Levels dialog box, you still have access to the scroll controls in the document window, the View menu, and to the hand and zoom tools by using keyboard shortcuts. See Shortcuts for more information.

4. To identify areas of representative highlights, neutral grays, and shadows in the image, do one of the following:
• Move the pointer around the image, and look at the Info palette to find the lightest, most neutral, and darkest areas. (See Using the Info palette.)
• View your image in Threshold mode in the Levels dialog box. See "To use Threshold mode to identify the lightest and darkest areas in an image" below.
5. Double-click the Set White Point eyedropper tool in the Levels dialog box to display the Color Picker. Enter the color values you want to assign to the lightest area in the image, and click OK. Follow these guidelines:
• When you are printing on white paper, you can achieve a good highlight in an average-key image using RGB values of 244, 244, 244. An approximate grayscale equivalent is a 4% dot.
• You can approximate these target values quickly by entering 96 in the Brightness (B) text box under the HSB section of the Color Picker.
• With a low-key image, you might want to set the highlight to a lower value to avoid too much contrast. Experiment with Brightness values between 96 and 80.
6. In the image, click the highlight you identified in step 4. If you accidentally click the wrong highlight, choose Edit > Undo Color Sample, and then try again.

The pixel values throughout the image are adjusted proportionately to the new highlight values. Any pixels lighter than the area you clicked become specular white. The Info palette shows the values both before and after the color adjustment.

7. Double-click the Set Gray Point eyedropper tool in the Levels dialog box to display the Color Picker. Enter the color values you want to assign to the neutral gray area in the image, and click OK. Assign equal red, green, and blue values to produce a neutral gray in an RGB image.
8. In the image, click the neutral gray you identified in step 4.
9. Double-click the Set Black Point eyedropper tool in the Levels dialog box to open the Color Picker. Enter the values you want to assign to the darkest area in the image, and click OK. Follow these guidelines:
• When you're printing on white paper, you can achieve a good shadow in an average-key image by using RGB values of 10, 10, 10. An approximate grayscale equivalent is a 96% dot.
• You can approximate these same values quickly by entering 4 in the Brightness (B) text box under the HSB section of the Color Picker.
• With a high-key image, you might want to set the shadow to a higher value to maintain detail in the highlights. Experiment with Brightness values between 4 and 20.
10. In the image, click the shadow you identified in step 4.
11. Click OK.

To use Threshold mode to identify the lightest and darkest areas in an image:

1. Do one of the following:
• Choose Enhance > Adjust Brightness/Contrast > Levels.
• Create a new Levels adjustment layer, or open an existing Levels adjustment layer. (See Using adjustment and fill layers.)
2. Select Preview in the Levels dialog box.
3. To view your image in Threshold mode, hold down Alt (Windows) or Option (Mac OS) and do one of the following:
• To view the lightest parts of the image, drag the white Input Levels triangle directly underneath the histogram. The visible areas of the image indicate the lightest parts of the image.
• To view the darkest parts of the image, drag the black Input Levels triangle directly underneath the histogram. The visible areas of the image indicate the darkest parts of the image.

If a single color channel is selected in the Levels dialog box, the black area indicates where none of the given color component exists.


Viewing in Threshold mode to identify the black point
4. Slowly drag the slider to the center of the histogram to identify the light or dark areas in the image. Use these pixels for targeting the black point and white point in your image.