Mask layers

You can add a mask to a layer and use the mask to hide portions of the layer and reveal the layers below. Masking layers is a useful for combining multiple photos into a single image or for removing a person or an object from a photo.

You can create two types of masks:

• Layer masks are resolution-dependent bitmap images that are edited with the painting or selection tools.
• Vector masks are resolution independent and are created with a pen or shape tool.

Layer and vector masks are nondestructive, which means you can go back and re‑edit the masks later without losing the pixels they hide. In the Layers panel, both the layer and vector masks appear as an additional thumbnail to the right of the layer thumbnail. For the layer mask, this thumbnail represents the grayscale channel that is created when you add the layer mask. The vector mask thumbnail represents a path that clips out the contents of the layer.

To create a layer or vector mask over the Background layer, first convert it to a regular layer (Layer > New > Layer from Background).

You can edit a layer mask to add or subtract from the masked region. A layer mask is a grayscale image. The areas you paint in black are hidden, the areas you paint in white are visible, and the areas you paint in shades of gray appear in various levels of transparency.

A vector mask creates a sharp-edged shape on a layer and is useful anytime you want to add a design element with clean and defined edges. After you create a layer with a vector mask, you can apply one or more layer styles to it, edit them if needed, and instantly have a usable button, panel, or other web-design element.

The Properties panel provides additional controls to adjust a mask. You can change the opacity of a mask to let more or less of the masked content show through, invert the mask, or refine the mask borders, as with a selection area.

When you add a layer mask, you can hide or show all of the layer, or base the mask on a selection or transparency. Later, you’ll paint on the mask to precisely hide portions of the layer, revealing the layers beneath.

To directly edit layer transparency, do the following and create a mask:

Photoshop converts transparency into an opaque color, hidden by the newly created mask. The opaque color varies greatly, depending upon the filters and other processing previously applied to the layer. This technique is helpful for video and 3D workflows.

Do one of the following:

• To move the mask to another layer, drag the mask to the other layer.
• To duplicate the mask, Alt-drag (Win) or Option-drag (Mac) the mask to the other layer.

By default, a layer or group is linked to its layer mask or vector mask, as indicated by the link icon  between the thumbnails in the Layers panel. The layer and its mask move together in the image when you move either one with the Move tool . Unlinking them lets you move them independently and shift the mask’s boundaries separately from the layer.

• To unlink a layer from its mask, click the link icon in the Layers panel.

• To reestablish the link between a layer and its mask, click between the layer and mask path thumbnails in the Layers panel.

Do one of the following:

• Select the layer containing the layer mask you want to disable or enable, and click the Disable/Enable Mask button  in the Properties panel.

• Shift-click the layer mask thumbnail in the Layers panel.

• Select the layer containing the layer mask you want to disable or enable, and choose Layer > Layer Mask > Disable/Enable.

A red X appears over the mask thumbnail in the Layers panel when the mask is disabled, and the layer’s content appears without masking effects.

You can apply a layer mask to permanently delete the hidden portions of a layer [*]. Layer masks are stored as alpha channels, so applying and deleting layer masks can help reduce file size. You can also delete a layer mask without applying the changes.

For easier editing of a layer mask, you can display the grayscale mask by itself or as a rubylith overlay on the layer.

Use the Properties panel to adjust the opacity of a selected layer or vector mask. The Density slider controls mask opacity. Feather lets you soften mask edges.

Other options are specific to layer masks. The Invert option reverses masked and unmasked areas. The Mask Edge option gives you various controls to modify the mask edges, such as Smooth and Contract/Expand. For information on the Color Range option, see Create and confine adjustment and fill layers.