Applying the Grow and Similar Commands in Photoshop

The Grow and Similar commands are close cousins to the Magic Wand tool. If you’re familiar with the modus operandi of the Magic Wand tool, you know that you rarely get the perfect selection on the first click. That’s because you are making an intelligent guess as to what Tolerance setting will pick up the pixels you want. The Grow command compensates a little for the Magic Wand tool’s inaccuracy. For example, if you need to include more in your selection, you can increase the Tolerance setting and try again — press Shift and click the area you need to include. Or you can choose Select➪Grow.

The Grow command increases the size of the selection by including adjacent pixels that fall within the range of Tolerance.
The Similar command is like Grow, only the pixels don’t have to be adjacent to be selected.
The command searches throughout the image and picks up pixels within the Tolerance range, wherever they may fall.

Both commands use the Tolerance value that is displayed in the Options bar when you have the Magic Wand tool selected. Adjust the Tolerance setting, to include more or fewer colors by increasing or decreasing the setting, respectively.