Add a Layer Mask in Photoshop
A layer mask in Photoshop is used to control a layer's transparency. It's great if you wish to reveal or hide portions of a layer using a mask. While you can use the Transparency control to adjust the opacity of a layer, using a mask gives you a lot more flexibility in what you show, and what you hide. Better still, you do it all without erasing a single pixel! We'll show you how to get the most out of this function.
Steps
Making A Layer Mask
- Select a layer. Highlight the layer you wish to mask. Make sure the layer is visible, or you will not be able to perform this function.
- Select an area. Using the the Marquee tool (press M to select it), select the area you wish to reveal.
- Note that if you want a soft edge, set the Feather radius as desired, before drawing the selection.
- Create the mask. Click the Add Layer Mask button at the bottom of the Layers palette.
- Alternatively, from the Layer menu, choose Layer Mask, then Reveal Selection.
- Admire your work. After adding the layer mask, the image will look like the one given right. Notice that the kitten's face remains revealed in the top layer, while the rest of the image is transparent, allowing the background layer to show through.
Adjusting A Layer Mask
- Fine tune your layer mask. Sometimes you want something a little more than a simple vignette, and do a little Photoshop magic with a layer mask. Here's how to do it.
- Set up your document's layers. In this example, we want a large mountain in the background, not the small one in the original image. We place the larger mountain image on the background layer, and the person's image with the small mountain in the layer above it.
- Draw your selection. This time, instead of using the Marquee tool, use the Pen tool (Press P to activate). Draw a path around the area you want selected, then adjust using the Direct Selection Tool (A).
- Convert to path. When you're satisfied with your selection, right-click on the path and choose Make Selection..."
- Set the selection values as desired.
- Click the Layer Mask button. You can also use the menu as described above. The selected area will remain, and the unselected area will be masked, revealing the layer below it.
- Edit the layer mask. If you should decide that you wanted more of the top image left in, you can paint the mask to reveal more of the top image. Select the Brush tool (B), set the foreground color to white, and paint back in the part you wish to keep.
- In this case, the foreground water was brought back into the image, and the mountain was adjusted to be more visible.
- Conversely, you can paint out the foreground layer by painting with black.
- Black is 100% transparent, and white is 100% opaque. You can also use shades of gray, which will make the mask semi transparent. For example, if you paint the layer mask 50% gray, you will partially reveal the background layer, and partly hide the foreground layer. This is good for reflections or other special effects.
Tips
- To duplicate the layer mask, click on the mask, hold down the Option or Alt key and drag to the layer where you want the duplicate mask to appear.
- To invert the layer mask, click on the layer mask and press CTRL+I (or on a Mac, Command +I)
