Use the Red/Green/Blue command to adjust the amount of red, green, and blue in your image to make color corrections by changing the overall color cast. To reduce the amount of a color in the image, you can either increase its opposite color on the color wheel or reduce the amount of adjacent colors on the color wheel. For example, to color correct an image containing too much yellow, either increase the amount of blue or decrease the amount of red and green.
Important: To apply this command to a selection, the image must be a 16 million (24-bit) color image (otherwise the command is applied to the entire image). To increase the color depth of an image, see Increasing the Color Depth of an Image.
To use the Red/Green/Blue command:
To limit the correction to a specific area, make a selection in the image. See Using the Selection Tools.
Choose Adjust > Color Balance > Red/Green/Blue.
In the Red, Green, and Blue edit boxes, select the percentage to change each value. A value of 0% indicates the original value. To add more of a color, use a positive number. To remove some of a color, use a negative number. Keep in mind the following:
Reducing the amount of blue adds a yellow cast to the image.
Reducing the amount of green adds a magenta cast to the image.
Reducing the amount of red adds a cyan cast to the image.
Click OK.
Adjusting the Hue Saturation and Lightness in Unison
Changing the Color Balance of Shadows, Midtones, and Highlights
Correcting Colors by Setting Black and White Points