Using the Selective Color command (Photoshop)

Selective color correction is a technique used by high-end scanners and separation programs to increase and decrease the amount of process colors in each of the additive and subtractive primary color components in an image. Even though Selective Color uses CMYK colors to correct an image, you can use it on RGB images as well as on images that will be printed.

Selective color correction is based on a table that shows the amount of each process ink used to create each primary color. By increasing and decreasing the amount of a process ink in relation to the other process inks, you can modify the amount of a process color in any primary color selectively--without affecting any other primary colors. For example, you can use selective color correction to dramatically decrease the cyan in the green component of an image while leaving the cyan in the blue component unaltered.

To use the Selective Color command:

1. Make sure the composite channel is selected in the Channels palette. The Selective Color command is available only when you're viewing the composite channel.
2. Open the Selective Color dialog box. (See Making color adjustments.)
3. Choose the color you want to adjust from the Colors menu at the top of the dialog box. Color sets consist of the primary additive and subtractive colors plus whites, neutrals, and blacks.
4. For Method, select an option:
• Relative to change the existing amount of cyan, magenta, yellow, or black by its percentage of the total. For example, if you start with a pixel that is 50% magenta and add 10%, 5% is added to the magenta (10% of 50% = 5%) for a total of 55% magenta. (This option cannot adjust pure specular white, which contains no color components.)
• Absolute to adjust the color in absolute values. For example, if you start with a pixel that is 50% magenta and add 10%, the magenta ink is set to a total of 60%.

Note: The adjustment is based on how close a color is to one of the options in the Colors menu. For example, 50% magenta is midway between white and pure magenta and will receive a proportionate mix of corrections defined for the two colors.

5. Drag the sliders to increase or decrease the components in the selected color.