How to Choke a Layer Mask in Photoshop

Photoshop layer masks are handy tools. When you mask out areas of a layer, they appear to be transparent just as they would be if you chose an element and moved it to a new layer. You can improve the quality of the selection edge, if you choke the layer mask.

Difficulty: Moderately Easy

Instructions

1. Use any selection tool or combination of tools to select the object you want to reveal. Click the "Add a Mask" button at the bottom of the layers palette. Everything else in the layer will become transparent and you will see a new black and white thumbnail in the payers palette (it resembles an alpha channel).

2. Choose "Contract" from the Select menu with your selection still active (the Contract command may be in a subfolder called "Modify" depending on which version of Photoshop you're using). Select the Contract value to 1 (2 if the image is larger than 72 pixels per inch). The selection edge will shrink slightly (this is called choking).

3. Apply the "Feather" command from the Select menu. Set the feather value to 1. You won't see any change, but the selection edge has now been slightly blurred.

4. Click on the layer mask thumbnail in the layers palette. You will see the four-corner border switch from the layer thumbnail to the layer mask thumbnail to indicate it is now active. If you don't see the border around the layer mask thumbnail, try again.

5. Invert the selection. Choose "Inverse" from the Select menu. You should now see the selection border surrounding the entire image as well as the original selection.

6. Fill the new selection with black. Your image won't change, but the selection will have a smoother, feathered edge. This will make it blend more naturally with any layers underneath.

Tips & Warnings

• If your image fills with black, you are still working with the image and not the layer mask. Undo immediately and make sure you click on the layer mask thumbnail in the layers palette.