The Brush tool, the Color Replacement too, the Pencil tool, and the Gradient tool. You can use each of them to select a foreground color by Option/Alt clicking in the image. Did you know that you can control how many pixels are used to determine that new foreground color? And it can be any color on your screen—it doesn’t have to be in your image!
All of the tools that can select a foreground color by Option/Alt clicking use the current setting for the Eyedropper tool. The Eyedropper tool can select the color of a single pixel on which you click, average that pixel with each neighboring pixel (3 by 3 Average), or use a radius of two pixels for the sample (5 by 5 Average).
To see how this makes a difference, take a look at the 25 pixel image (5 pixels by 5 pixels) in the following image and see how the foreground color (in the Toolbox) changes depending on the Eyedropper setting in the Options bar.
When Point Sample is selected, only the center pixel is sampled. With 3 by 3 Average selected, the nine pixels in the center are averaged to create the next foreground color. With 5 by 5 Average selected, all 25 pixels are averaged. (By the way, the “3 by 3” and “5 by 5” are just a bit misleading – if you click on a pixel in the corner of the image or along an edge, only the pixels adjacent to the pixel on which you click are used, not a full 9 or 25 pixels.)
The Eyedropper tool (or any of the tools that use the Eyedropper when the Option/Alt key is down) can sample anywhere on the screen, not just in your image. Click in your image and continue to hold the mouse button down. Move the cursor anywhere on screen and, when you’re over the color you want to select, release the mouse button.
Pete
Bauer is the Help Desk Director for NAPP, as well
as a Contributing Writer for Photoshop User and Mac Design
magazines. His books include "Special Edition Using
Adobe Photoshop 7" (with Jeff Foster), "Special
Edition Using Adobe Illustrator 10," "Sams Teach
Yourself Adobe Illustrator 10 in 24 Hours" (with Mordy
Golding), and "Special Edition Using Adobe Illustrator
9." Pete writes documentation for a variety of computer
graphics related products, as well as testing software
for a number of companies. As a computer graphics efficiency
consultant, Pete specializes in customized training programs.
He is based in Columbus, Ohio, and can be contacted via
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