Software Workshop: Masking 101

Learn the basics behind this most important skill.

april11softmain.jpg
This picture needed more contrast in the background, but not on the rocks. Masks made it happen. If you have Adobe Photoshop and don’t know how to use Masks, you’re wasting the program’s power. Masks, when used in combination with Layers or Adjustment Layers, are the single best way to adjust specific zones of your image independently. All you have to do is make a change to your image on one layer, add a mask, then use the mask to hide or reveal the change you made—only in the areas where you want to see it. This works when you want to add, say, contrast, saturation, or sharpness to a specific zone. Masks are also useful in compositing. Here is a tutorial that focuses on the basics of the ways Masks function. Follow these steps, and you’ll be able to translate your knowledge to making targeted adjustments to your pictures. These instructions are for Photoshop CS5, but are simple enough to be used in any modern version of Photoshop, as well as Photoshop Elements 9. (Previous versions of Elements have Mask functionality only with Adjustment Layers.) Tips and Shortcuts:
To hide your mask, hold down the Shift key on your keyboard and click on the layer's mask icon (you'll see a red X when it's hidden). Shift + click again to get rid of the X. To see the mask itself, hold down the Alt key (Option on a Mac), and click on the mask icon. This can be useful to check if you've missed a spot. Click on the main layer thumbnail or another layer to return your view to normal.
Saleh Alrashaid
april11softstep01.jpg
Step 1
Masks can be confusing because you can't see them, so here's a demo that will make learning the basics simple. First, duplicate your background layer. Then go to Image > Adjustments > Desaturate. This will take all the color out of your Background copy layer. Now add a mask. To do so, just click on the mask button. (Desaturate is a terrible command for converting to black- and-white, but it works for the purposes of this workshop)
Saleh Alrashaid
april11softstep02.jpg
Step 2
Click on the thumbnail for the mask to make sure it's selected. When it is, you'll see an extra box around it. Now type B on your keyboard to get the Brush tool. Unless you elect to see your mask (see F.Y.I.), it will be invisible. But since it's selected, you can use it to hide and show the layer underneath. Make sure black is the foreground color in the toolbar, and paint on your image to reveal the layer below. (As long as your mask is selected, only black and white will show up in your color swatches in the toolbar.)
Saleh Alrashaid
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Step 3
Black hides, white reveals—understand that and you've got masks cracked. Check out the thumbnail for your mask; it shows you a map of where you've painted. Most of Photoshop's usual tools work on masks as they do on normal layers. With your mask still selected, go to Edit > Fill. Choose Use: Black from the pulldown menu and click OK. Since your whole mask is now black, you can only see the layer below. Switch your brush to white, and paint to reveal the top layer. (This technique is great when you want to make a change to a small area.)
Saleh Alrashaid
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Step 4
While masks work great with normal layers, with Adjustment Layers they're a match made in heaven. Delete the Background Copy layer you've been practicing on, and create a Curves Adjustment Layer by clicking on its icon in the adjustments panel. When you make a new Adjustment Layer, a mask is automatically created with it. Now adjust the curve. In this case, the towers could use some more contrast.
Saleh Alrashaid
april11softstep05.jpg
Step 5
The contrast really helps the elements in the background of the image, but it is far too strong for the foreground. So use the technique from Step 2 to hide the adjustment on the rocks. Grab the Brush tool, make sures your mask is selected, then paint on the rocks to hide your contrasty adjustment. To see the effect before and after, click the eyeball icon for the layer (in the Layers Panel) on and off. Often, you’ll need multiple Adjustment Layers, with masks on each.
Saleh Alrashaid