A clipping mask lets you use the content of a layer to mask the layers above it. The masking is determined by the content of the bottom or base layer. The non-transparent content of the base layer clips (reveals) the content of the layers above it in the clipping mask. All other content in the clipped layers is masked out.
You can use multiple layers in a clipping mask, but they must be successive layers. The name of the base layer in the mask is underlined, and the thumbnails for the overlying layers are indented. The overlying layers display a clipping mask icon.
The Blend Clipped Layers As Group option in the Layer Style dialog box determines whether the blending mode of the base affects the whole group or just the base. (See Group blend effects.)
- Hold down Alt (Windows) or Option (Mac OS), position the pointer over the line in the Layers panel dividing the base layer and the first layer above it that you want to include in the clipping mask (the pointer changes to two overlapping circles ), and click.
To add additional layers to the clipping mask, use either method in step 2, and work your way upward one level at a time in the Layers panel.
If you create a new layer between layers in a clipping mask, or drag an unclipped layer between layers in a clipping mask, the layer becomes part of the clipping mask.