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Tutorial: Using Layer Masks

(Continuation from the "Cutting Out an Image" Tutorial)

A layer mask is a powerful feature that allows you to show and hide specific parts of a layer in very detailed and flexible ways. By using a layer mask, your work remains flexible--a mask can be modified at any time.Finished Image

In this tutorial, we are going to continue creating the image to the right. In the first section of the tutorial, we cropped and straightened the background and selected the sailor using these files: Meredith.jpg  sailor.jpg

So far, we have already selected the Sailor using the Quick Selection Tool quick selection tool

Not using CS3 or later? Advanced Selection Techniques coming soon!

Sailor selected

Now, we need to make sure we can add a Layer Mask

Before adding a mask to a layer, we have to make sure that the layer is capable of being masked. If your layer is a locked background layer, it needs to be converted into a regular layer before you can add a mask. Simply Double-Click on the layer and click Ok to convert it, and the lock icon will dissapear.

Why is there a locked background layer?

Some image formats, like jpg, do not store transparency information.When you open one of these formats in Photoshop, the background layer is locked, preventing you from adding tranparency information. We convert the background layer into a regular layer so that we can hide portions of the layer.

Unlocking a layer

Finally, we can add a Layer Mask

With the sailor selected, you can open the Layer menu and select Layer Mask > Reveal Selection. This will create a mask that hides everything on the layer except the sailor that you selected.

There is a quick shortcut to add a layer mask, too. Instead of using the Layer menu, you can simply click the "Add Layer Mask" button at the bottom of the Layers panel.

Two ways of adding a Layer mask (Click to expand)

Both methods, side by side


How Layer Masks work: A side note

Before continuing, let's take a moment to discuss how a layer mask works. It is important to understand why the technique above produces a cut-out of your image.

A layer mask is a greyscale image that affects the visibility of the layer that it is attached to. When a layer mask is black, the contents of its layer are hidden. When a mask is white, the contents are completely visible. Shades of grey make the contents partially transparent. Compare the ordinary document below with the two layer mask examples to see how layer masks can affect layers.

Ordinary Layers
An ordinary document, with no layer masks added.

Example: a circular cutout mask (Click to expand)

Layer Mask Added
Layer mask with a black circle added--a portion of the top layer is hidden.

Example: a gradient mask (Click to expand)

Layer Mask with a gradient
Layer mask with a gradient added--the layer's visibility varies as the gradient changes.

Masks provide a very flexible and non-destructive way to modify the appearance of a layer. Most of the drawing tools, filters, and image adjustment features provided by Photoshop can be used with layer masks, so as you learn more advanced editing techniques, this feature will become increasingly useful.


Take a look at the mask you've just created

Now we know that in the world of layer masks, Black means "show" and White means "hide." When you create a selection and add a layer mask, Photoshop automatically creates a black and white image based on the selection. At this point, you can adjust the borders of your mask using the Masks Panel (new in CS4) or by using painting tools and image filters. This method is much more flexible than copy and paste because you can add to or subtract from your mask at any time as you create your final image.

This section is complete!

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Last modified: May 04, 2007, 08:28 EDT
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