When you select part of an image, the area that is not selected is masked, or protected from editing. So, when you create a mask, you isolate and protect areas of an image as you apply color changes, filters, or other effects to the rest of the image. You can also use masks for complex image editing such as gradually applying color or filter effects to an image.

Masks are stored in alpha channels. Masks and channels are grayscale images, so you can edit them like any other image with painting tools, editing tools, and filters. Areas painted black on a mask are protected, and areas painted white are editable.

Use Quick Mask mode to convert a selection to a temporary mask for easier editing. The Quick Mask appears as a colored overlay with adjustable opacity. You can edit the Quick Mask using any painting tool or modify it with a filter. Once you exit Quick Mask mode, the mask is converted back to a selection on the image.

To save a selection more permanently, you can store it as an alpha channel. The alpha channel stores the selection as an editable grayscale mask in the Channels panel. Once you store the selection as an alpha channel, you can reload it at any time or even load it into another image.

Create and edit alpha channel masks

You can create a new alpha channel and then use painting tools, editing tools, and filters to create a mask from the alpha channel. You can also save an existing selection in a Photoshop image as an alpha channel that appears in the Channels panel. See Save and load selections.

Create an alpha channel mask using current options

Create an alpha channel mask and set options

Edit channel options

To change options for an existing channel, double-click the channel thumbnail in the Channels panel or select Channel Options from the Channels panel menu.

Options available in the New Channel and Channel Options dialog boxes:

Sets masked areas to black (opaque) and selected areas to white (transparent). Painting with black increases the masked area; painting with white increases the selected area. When this option is selected, the Quick Mask button in the toolbox becomes a white circle on a gray background .

Sets masked areas to white (transparent) and selected areas to black (opaque). Painting with white increases the masked area; painting with black increases the selected area. When this option is selected, the Quick Mask button in the toolbox becomes a gray circle on a white background .

Converts an alpha channel to a spot color channel. Only available for existing channels.

Sets the color and opacity of the mask. Click the color field to change the color. The color and opacity settings affect only the appearance of the mask and have no effect on how underlying areas are protected. Changing these settings may make the mask more easily visible against the colors in the image.

Paint on a channel to mask image areas

When the new channel appears at the bottom of the Channels panel, it is the only channel visible in the image window. Click the eye icon  for the composite color channel (RGB, CMYK) to display the image with a color overlay showing the mask.

Save and load selections

You can save any selection as a mask in a new or existing alpha channel and later reload the selection from the mask.

You can use a selection as a layer mask by loading the selection to make it active, then adding a new layer mask.

Save a selection to a new channel

Save a selection to a new or existing channel

Load a saved selection from the Channels panel

You can reuse a previously saved selection by loading it into an image. You can also load the selection into an image after you finish modifying an alpha channel.

Load a saved selection