The creative tutorial home of image wrangler, Lesa Snider.

Tough Selections, Part 1

September 20, 2006 by
The magic of the Background Eraser
The magic of the Background Eraser

Conquering tough selections means having many tricks up your sleeve. Chances are, no one tool is going to get you where you want to go, but the wisdom lies in starting out with the tool that'll get you the farthest.

In this new tutorial series, we''ll discuss several methods for getting at those really tough selections which aren't suited for selecting by shape or color. Let us start off by using an oft forgotten selection tool, the Background Eraser, on a beautiful photo of Old Glory snatched from iStockphoto.com.

Save thyself from thyself

The thing to remember about using the Background Eraser is that it's destructive, meaning it will delete pixels leaving no room for error. Luckily, there's an easy way to use its power in a non-destructive manner. Read on!

Step 1: Open the offending photo and double-click the background layer to make it editable. Immediately press Command + J (PC: Ctrl + J) to duplicate the layer, and then turn its visibility eyeball off, as shown below.

Step 2: For the purpose of this tutorial, I added a new layer by pressing the New Layer icon at the bottom of the Layers Palette (circled below in red), and filled it with white (so you can actually see what I'm doing). TIP: Press D to set your color chips to the default of black and white, then press X until white is perched happily on top. Press Option + Delete (PC: Alt + Delete) to fill the new layer with white. This is what my Layers Palette looks like now:

Step 3: Grab the Background Eraser Tool from the main toolbox (it's hiding within the Eraser Tool).

Paint away the background
Step 4: This particular tool uses a brush cursor, as shown below and the trick is to position it so that the tiny plus sign within the brush does *not* touch the colors you want to keep. Begin to brush away the background, as shown below:

TIP: Cycle down in brush size by pressing the left bracket key, [, and cycle up in by pressing the right bracket key, ].

Tweak the tolerance

Step 5: As you can see, this tool is doing a terrific job of erasing the sky background. However, when I get near the white bits of the flag, things get a little dicey, as shown below.

The fix is to decrease the tool's tolerance in the options bar at the top of your screen.

Now the white areas of the flag are not being affected. Chances are you may do quite of bit of tolerance adjusting, depending upon the amount of contrast between objects in your photo.

NOTE: On the area between the rope and the flag's edge, I had to zoom in really far and be very careful painting in between, as shown below:

Once you finish outlining the area you want to keep, you should have something like this:

Erase the rest

Step 7: Now that we have a clean outline around the edge of the flag and pole, we can switch to the regular Eraser tool and zap the remaining sky.

Here's what we see with the white layer turned off:

Apply a mask

Step 8: Create a selection around the flag and pole by Command (PC: Ctrl) clicking the layer thumbnail in the Layers Palette, as circled below. This will cause marching ants to dutifully surround everything on that layer.

Step 9: With the marching ants still visible, turn the visibility eyeball off for the top layer, and turn it on for the bottom layer (the one with the sky still intact). Create a Layer Mask by clicking the circle within a square icon at the bottom of the Layers Palette (circled in red below).

See the wisdom of duplicating that background layer? We've built in the ability to tweak the selection in case our first Background Erasing Attempt wasn't 100% perfect.

That's all for now; see you next week!