Increasing and Decreasing Color in Photoshop

Increasing and decreasing color is a popular Photoshop activity, so having more than one way to do it is no surprise. In addition to the Selective Color command, which I describe in the following section, several other commands are a lot easier to understand — and a lot easier to use. This is the place to start reading if you want to know all about the Gradient Maps command, and the various color mapper tools, all of which are designed to change the arrangement of the colors in your photos in ways that don’t produce realistic-looking images. Images that have been color-mapped are certainly interesting to look at.

Using the Selective Color command
The Selective Color command is chiefly of use for manipulating the amount of process colors (that is, cyan, magenta, yellow, and black) used in printing an image. In the Selective Color dialog box, choose the color you want to edit from the Colors pop-up menu. Adjust the CMYK sliders to modify the selected color. With the Relative method selected, you can add or subtract color. For example, if a pixel is 30 percent cyan and you add 20 percent cyan, Photoshop adds 6 percent cyan to the pixel (20 percent of 30 percent is 6 percent).

With the Absolute method selected, Photoshop bases the amount of change on the exact value you enter. For example, if a pixel is 30 percent cyan and you add 20 percent cyan, the pixel changes to a total of 50 percent cyan.

Using gradient maps
Gradient maps convert your image to grayscale, and then replace the range of black, gray, and white tones with a gradient of your choice, in effect colorizing your image — often in startling ways. Photoshop maps the lightest tones of your image to one color in the gradient and changes the darkest tones to the other color of the gradient (assuming you’re using just two colors for the gradient). Photoshop changes all the formerly gray tones to an intermediate color between the two. When you use multiple colors or fancy gradients, the image really gets interesting. Just follow these steps to try out this feature:

1. Open an image and access the Gradient Map by choosing Image-->Adjustments-->Gradient Map.
2. Choose the gradient you want from the gradient list.
This list is exactly like the one offered with the Gradient tool. You can edit the gradient used for your map exactly as you do for the Gradient tool.
3. Choose either or both of these options:
- Dither adds random noise to smooth out the gradient and reduces banding.
- Reverse changes the direction of the gradient.
Use the Reverse option to reverse the image (creating a negative) quickly.
4. Click OK to apply the gradient map.
If the effect is a little too intense for your taste, try fading the gradient map (Edit-->Fade Gradient Mask) and then adjusting the Opacity percentage and/or applying a different blend mode.