Photoshop Tip: Combining Selections

PHOTOSHOP TIP: Combining Selections
by Michael Frye

In Photoshop, selections allow you to adjust a designated area of your photograph without affecting the rest of the image. This is particularly useful when you want to darken the sky without darkening the foreground of a photograph, for example. There are many ways to make a selection. For photographs, some of the most useful tools are the Lasso, Magnetic Lasso, Magic Wand, and Color Range. How to use those tools is beyond the scope of this little tip, but what many people don't realize is that you can easily combine selections together to create new ones.

In the image of Delicate Arch above, let's say that I made selections for the arch (lit by a flashlight at dusk, by the way), and the black areas in the bottom half of the photo. But now I want to work on just the sky. Do I have to start all over? Luckily, no, because I've saved the previous selections. If I combine those two selections, the only area not selected would be the sky. All I have to do is invert the selection, and presto, only the sky will be selected.

1. Name your selection
It's a good idea to save any selection you've worked on for more than two minutes. Once you've made a selection and you have the moving, dashed lines on your screen (the "marching ants"), go to Select > Save Selection.

You'll see a dialog box that looks like this:

Leave the defaults alone (i.e. Channel: New and Operation: New Channel). Give your selection a name you'll remember. For example, I named the selection for the arch the creative name of "Arch." Then click OK.

2. Look at your Channels Palette
If you look at your Channels Palette, you'll see a channel with the name you've just given it. Let's say I've saved selections for both the arch and the black background. My Channels Palette now looks like this:

3. Combine Two Selections
To combine two selections, you have to load one first.

• Either go to Select > Load Selection and choose the name of the desired channel, or just Command-Click (Windows: Control-Click) on the name of the channel in the Channels Palette.

• Once you have your first selection loaded (the ants are marching), go to Select > Load Selection.

You'll see a dialog box that looks like this:

• For Operation, choose Add to Selection.

• For Channel, select the name of the channel you want to add. For example, if I've already loaded the "Arch" selection, I'll add the "Black" channel, as shown above.

• Click OK and you've combined the two selections. Now I have the arch and the black background areas selected. The only thing not selected is the sky.

• Go to Select > Inverse, or just press Shift-Command-I (Windows: Shift-Control-I) to select the sky.

One Caveat:
Adding channels (by saving selections) increases your file size; a complicated selection/channel can fatten your file by 25% or more. So it's a good idea to delete these channels when you're sure you won't need them any more. Just drag the channel to the little trash can at the bottom of the Channels Palette.