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6 Steps to Using Masks in Photoshop

What is a Mask?

If you want to do precise blending of foreground and background elements in Photoshop, it is essential to learn to use layer masks. Layer masks allow you to endlessly modify and edit your image while still keeping your original intact.

A mask is attached to a specific layer in order to occlude portions of that layer. It is like using "invisibility ink" that you can paint or erase on a layer. In this way, you can hide part of an image on a given layer and reveal whatever is on a lower layer.

The following diagrams show a mask applied to an image:

Mask concept

The mask in the above example is a simple circle, which acts like a stencil placed over the image. In this case, the masked-out portion is shown as 100 percent black. In Photoshop,when a mask is painted black, the solid black portion of a mask completely hides the contents of its attached layer. On the other hand, the white part of a layer mask allows everything on the associated layer to show. Since a mask is attached to a layer as a separate part, the layer’s original pixels are not affected. This allows us to modify the mask as many times as we wish, or even delete it and start again.

Why Would You Use a Mask?

When you want to blend two layers together, but you want to finely edit the transitional areas, use a layer mask. It offers you more control than simply selecting a piece of a layer and deleting it, because it doesn't actually delete pixels. Instead, you can use any of the Photoshop painting tools to hide or show parts of a layer.

How Do You Create a Mask?

1. Open an image in Photoshop.

2. If you do not see the Layers palette, from the Menu bar, click Windows and choose Layers from the drop-down.

Now, if you will be blending two or more images together, you will need to have each image on a separate layer.

3. To add a layer containing a second image:

(Photoshop CS2 and CS3) from the Menu bar, click File and choose Place from the drop-down menu. Find the image and click Place.

(Photoshop 8 and below) Open a second image. Move the Title bars apart so you can see both images. With the Move tool move tool, press and drag one of the images right on top of the other. Release the mouse.

In the Layers palette, you should now see two layers:

4. Click the top layer in the Layers palette.

Now, you can add the Layer mask.

5. In the Layers palette, find and click the Add layer mask icon layer Mask Button.

You will see something that looks like this:

6. Make sure that the Layer Mask icon is active in the Layers palette, as indicated by the border around it:

7. Now, click the Brush tool

Wherever you paint, the layer will disappear. To make those pixels visible again, use the Eraser tool

Remember, in a layer mask, painting with black conceals the pixels in the layer, and painting with white reveals them.

To learn more about layer masks and find more tips and tricks in Photoshop, consider taking the Photoshop: Restoring and Blending Images self-study tutorial offered through IT Training and Education at Indiana University. IT Training & Education offers instructor-led computing workshops and also provides self-study training resources to the Indiana University community and beyond. We deliver training to more than 30,000 participants each year across all campuses through our instructor-led workshops and self-study training resources. Our goal is to provide you with excellent technology training and customer service. We continue to be dedicated to meeting the training needs of all of our participants, from the true beginner to the more advanced user.

See the workshop topics at http://www.ittraining.iu.edu/workshops/workshop_groups.aspx and order materials up at http://www.ittraining.iu.edu/materials/.

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