Lesson F: Selections & Masking

Selections are a big part of Photoshop. They’re how we tell the application which pixels we want to affect. Masks are a means of hiding pixels, areas of an image we don’t want to see. We could delete those pixels, but we might regret it. I make mistakes and change my mind sometimes, and so do my clients. You too? Hiding areas with a mask means we can reveal those pixels if minds change or errors are discovered. That’s why masking is considered a best practice.

Masking Metaphor

Let’s borrow a visual from the “Selections & Masks” chapter of the Compendium. You really should check out “A Metaphor and Example” (page 286) for the full story. But in brief, a mask acts like a kind of light-block that prevents the entire image from being visible. And it does this without damaging the image.

A Warm-Up

Let’s briefly return to the image called “trading faces.psd.” It’s got two layers and, like our Italian scene, the top one needs to lose some content so it can blend in with what’s below.

Basic Procedure to Make a Mask

The first thing to do is to indicate which pixels should remain visible. For this image, that will be the central parts of Mona Lisa’s face.

In this case, we don’t need high precision, so we’ll select that area with the Lasso tool (L).

• Make sure the “familiar face” layer is highlighted.
• Tap the L key to activate the Lasso tool. Some tools have intuitive shortcuts like that, most don’t. Look at the Tools panel and you’ll see that the Lasso tool is now active.
• Press and drag to draw around the main parts of her face. You don’t need to be too careful this time. But if you really are unhappy with the first attempt, click just once outside your current selection and then try again.
• You now have a selection marquee (nickname: “marching ants”). You’re ready to make the mask.
• Click the Add layer mask button () at the bottom of the Layers panel, or choose Layer > Layer Mask > Reveal Selection. I know it looks pretty bad so far.
• Open the Properties panel. Choose Window > Properties to do so. The Window menu is where all Photoshop’s panels are listed.

Basic Mask Properties

Since you just created the mask, it is targeted, or active. If you look carefully at the Layers panel, you’ll see little brackets around the mask thumbnail that has appeared on the “familiar face” layer. The Properties panel will also indicate that the mask is the active part of the active layer. If you click once on the image thumbnail, the Properties panel will say “Pixel Layer” at the top. Clicking on the mask thumbnail shows the mask’s properties. We’re going to blur (or feather) this mask.

• Drag the Feather slider (or scrub the word “Feather”) until her face is blending in a bit with his head. I find that a value of about 20 pixels works well in this case.

The edges of the familiar face are now translucent, fading away to cause this blending. If you were to disable the visibility of the grumpy face layer, you’d see her face fading into a checkerboard pattern (Photoshop’s way of indicating transparent areas).

When I adjusted Feather, the result was pretty good, except on the left side where some of her hair was still visible.

Take a good look at that mask thumbnail. Notice that it’s black where pixels are hidden and white where they’re shown. If we paint with black on that mask, we’ll hide those last bits. Painting with white reveals pixels again.

Painting on Masks

Again, be sure the mask thumbnail is active.

• Choose the Brush tool by tapping the B key.

Note near the bottom of the Tools panel that the Foreground and Background colors are white and black (the defaults). If not, tapping D for “default” makes it so. When you paint, it’s the Foreground color that gets applied. We want that to be black so we can hide the last bits of the Mona Lisa image. If the colors are in the wrong position, click the two-headed arrow near those color chips to swap them, or tap the X key to do so. I told you some shortcuts are not intuitive.

• Ensure the Foreground color is black.

The brush is likely too small if it’s still at its default size. Also, it’s likely a round, fuzzy brush, which is the perfect character for our mask.

• Resize the brush by using the square bracket keys ([ and ]), using the right bracket to make the brush bigger. It appears I went with a brush that is 70 pixels across. You can check the size at the top of the screen in the Options Bar.
• Press and drag to paint along the left side of her face (I suppose it’s her right side, but it’s to our left).

As you paint, it looks like erasure, but the pixels are merely being hidden. If you were to paint with white, they would reappear.

The grumpy face is now obscured by Mona Lisa’s more pleasant, if mysterious, one.

• Choose File > Save, then either choose File > Close or click the small X in the image’s tab.

A Few Possible Methods

Now back to our osprey and quaint Italian hill town in town_too_blue.psd. We need to select the osprey, then, when we add the mask, all else on that layer will be hidden. There are several tools that allow us to select subjects against homogeneous backgrounds like that blue sky around the raptor. For much, much more on the following selection methods, set aside time to peruse the “Selections & Masks” chapter of this book’s Compendium.

• Highlight the osprey layer, then select the Object Selection tool (W; or fourth from the top).

Select Subject

This is a relatively new method. It’s also under ongoing development, so if it doesn’t work as you expect today, try it again when there’s an update to Photoshop.

• When certain selection tools, like the Object Selection tool, are active, the Select Subject button appears in the Options Bar. Click it! If another tool is active, you can access this function from the Select menu by choosing Select > Subject.
• As of this writing, this command does a nearly perfect job. However, it doesn’t quite capture the feathers at the wingtips well enough. Perhaps by the time you read this, it will.
• Since this isn’t quite right, and we wish to try something else, choose Select > Deselect or use the shortcut ⌘-D/Ctrl-D.

Object Selection Tool Intro

• This tool is like a guided Select Subject. Use it to draw a box around the osprey, and it will do a fairly good job as well. But again, it lacks where there are tight twists and turns.
• Since this isn’t quite right, and we wish to try something else, choose Select > Deselect or use the shortcut ⌘-D/Ctrl-D.

Quick Selection Tool Intro

This tool is a little more work. With it, we “paint” over material we want selected and it learns about the colors and textures we’re after. I find that if you paint a little, release, paint a little more, release, etc., it does better than if you try to paint over an entire object at once. This is true, at any rate, for subjects more entangled in their environments than a bird of prey. With this image, you may do well enough by painting continuously over the osprey.

• Right-click on the Object Selection tool to reveal the tools hidden behind it. One is called the Quick Selection tool—choose it. The cursor will be a smallish brush (a circle).
• Keeping the cursor within the bird’s perimeter, paint over its length. Avoid getting too close to the edge of the subject. If the brush touches blue sky, stop, undo, and try again more carefully.

If we were to zoom in and use progressively tinier brush sizes, we would be able to select the osprey very well. However, we should note that the bird is in front of a backdrop that’s very different than it is in color and tone. And just as moviemakers use blue and green screens to isolate subjects and put them in different circumstances, so can we.

• There’s an easier way for this image, so choose Select > Deselect or use ⌘-D/Ctrl-D.

Magic Wand

To use this tool advantageously, we have to know there exists a command that inverts a selection: selecting what wasn’t, and deselecting what was. We note this because the blue pixels and the transparent ones surrounding the bird are very easy to select. We can then invert that selection to have a very precise selection of our subject.

• Right-click on the Quick Selection tool to reveal the Magic Wand tool—choose it. The cursor will resemble the tool icon, a magic wand. Since this is the oldest of these tools, I sometimes call it the Elder Wand.
• Click once on the transparent pixels surrounding the entire osprey layer.
• Then, to add the blue pixels to that selection, hold down the Shift key and click on part of the blue sky around the osprey. You now have a great selection of everything except the bird.
• Choose Select > Inverse. Awesome!
• Click the Add layer mask button () at the bottom of the Layers panel, or choose Layer > Layer Mask > Reveal Selection.
• Switch to the Move tool (V) and drag the bird wherever you want it.