Layer Masks

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Web Graphics

February 7, 2008


In many graphics programs, you can add a layer mask to a layer to change how the layer's pixel opacity interacts with the layer below.

A layer mask is a special black and white mask that enables you to hide pixels on a layer, showing pixels on the layer below. A layer mask is always attached to an individual layer and works to hide or show the pixels on the layer to which it is attached. In the Layers palette, a layer mask appears as a thumbnail linked to the layer's own thumbnail.

Layer Mask Layers Palette
Layer mask Layers palette with mask

Why Use Layer Masks?

Layer masks are very useful and versatile tools. By using layer masks, you can make changes to your images non-destructively becasue you do not change the pixels on the original image. You can modify the mask as many times as you want and never lose the original image. Using a layer mask, you can:

  • Combine two or more pictures quickly and easily.
  • Add interesting frames to your photos.
  • Apply effects to the layer mask to add interesting effects to your images.

Painting the Layer Mask

When you first create a layer mask, the mask is filled with 100% white and all the pixels on the attached layer are visible. To hide pixels and allow pixels on the layer below to show through, you can paint on the mask in 100% black. To change the opacity and allow some of the pixels in the layer below to show through, you can paint on the mask with shades of gray.

  • Black hides the pixels on the attached layer to reveal the pixels on the layer below.
  • White shows the pixels on the attached layer.
  • Shades of gray change the opacity of the attached layer to reveal the pixels on the layer below.

Example

In the following example from Adobe® Photoshop® CS2:

  1. Layer 1 is filled with blue.
  2. Layer 2 is filled with green and a layer mask is applied.
  3. Using the Shape tool, a black heart shape is painted in the layer mask, allowing the blue pixels to show through.
Result Layers Palette
Layer mask result Layers palette with mask

 

Related articles

Photoshop Elements: Create a Layer Mask
Photoshop Elements: Merge Two Images With a Layer Mask

Updated on April 4, 2008