If you’ve used Photoshop for image-editing, you know that the popular program can sometimes be a little intimidating for newcomers. One of the advanced, but vital tools you’ll need to get to grips with eventually is the humble layer mask. This feature allows you to alter small parts of an image, leaving other parts untouched.
In this guide, we explain all of the steps you need to follow to create a layer mask. Once you know how to create a layer mask, you can edit small parts of your images without having to change the entire thing.
What is a Photoshop layer mask?
A layer mask makes a portion of that layer invisible, revealing the layers underneath, while keeping other parts of the layer intact. Unlike making a selection to copy and paste into a new layer, a layer mask allows you to go back and make adjustments to what’s included in the selection (and what’s not included) at any point in the editing process.
Say you are compositing a person onto a new background. Halfway through the editing process, you realize you cut off part of that person’s hair. If you copied and pasted that person using one of Photoshop’s selection tools, you’d have to start over from the beginning, making a whole new selection. With a layer mask, it’s no big deal — simply adjust the mask to include the missing hair, and continue working.
A layer mask is basically a monochromatic layer. Paint it all black to fully hide of the underlying layer, or all white to fully reveal it. It can also handle any shade of gray, which will partially hide the underlying layer. You can use the paint brush, paint bucket, or even gradient tools to create all shapes and sizes of masks.
Selecting an object, then, is about painting black over everything you don’t want to include — or, by starting with a filled-in mask and painting white over what you do want to include. At any time during the editing process, you can go back and use black, white, and gray paint brushes to fine-tune the selection.
Layer masks work with both regular layers and adjustment layers. When you add a new adjustment layer in Photoshop, a new layer mask is automatically created — you just have to use the brush to make the selections, or leave the mask alone to adjust the entire image. This is a great way to adjust, say, the brightness and contrast of just one particular element in a photo.
How to create (and work with) layer masks in Photoshop
1. Create a multi-layer document.
If you create a layer mask from a file with just a single background layer, you will create a cut-out on a transparent background.
If you want to make selective adjustments to the photograph without deleting the background, you’ll want to work with adjustment layers. Photoshop automatically creates a layer mask for each new adjustment layer. Adjustment layers are best for tasks like selectively adjusting the exposure or color.
To create an adjustment layer, click the half-colored circle at the bottom of the layers panel (or from the menu bar, choose Layer > New Adjustment Layer) and select the type of adjustment layer to create. An exposure adjustment layer will selectively adjust the exposure for only the masked area of the image, for example.
Another popular use for layer masks is composting, or merging multiple photos together. To work on a composite, start by creating a layer for each image that you want to merge into the final copy.
2. Decide whether to start with a layer, or a selection.
You can start a layer mask from a selection, or just from a layer itself. Starting from a selection allows you to use Photoshop’s different selection tools to jump-start your layer mask. In many cases, using Photoshop’s Select Subject or Object Selection tool is the fastest way to make the initial mask.
If you decide to start from a selection, use your favorite selection tool to first make a selection from the layer you’d like to adjust. In the photo above, I used Select > Color Range to get a quick selection. You can also use the new Select Subject, Object Selection tool, the magnetic lasso, the magic wand, or the quick selection tool. Don’t worry about getting the selection just perfect, that’s what the layer mask is for.
If getting the selection is easier with a paintbrush, then go straight to making the layer mask button without making a selection first.
3. Hit the layer mask button.
If you made a selection, make sure the selection is still active with those dotted lines or marching ants. If you decided to start with just a layer instead, make sure the layer that you’d like to mask is selected inside the Layers panel.
Next, inside the Layers panel, hit the add layer mask button (it’s the icon that looks like a white rectangle with a circle cut out of the middle). You will then see a white box appear next to the name of the layer, or a white box with a black shape that’s identical to the selection you made. This is the layer mask. (When working with an adjustment layer, you do not need to add a layer mask, since Photoshop adds them for you.)
Hint: If you don’t see the layers panel, navigate to the Window menu make sure Layers is checked, or hit F7 on the keyboard.
4. Create a selection with the layer mask.
The white rectangle on the layer inside the layers panel is your layer mask. When adjusting the mask, make sure this mask is selected — a white outline will appear at the corners when the layer mask is selected.
With the layer mask created, making a selection is as simple as coloring what you want to be visible in white and what you want to be invisible in black. If your foreground and background colors at the bottom of the toolbar on the left are not black and white, hit D on the keyboard to quickly bring up those colors. To switch your brush color from the color that’s on top to the color that’s on the bottom, hit the X key.
Use Photoshop’s color tools to fine-tune your mask so that what you want visible is white and everything else is black. Using the paintbrush tool, you can paint white over the areas of the image to include. Inside the brush options, look for a brush that best suits the task. A brush with a hard edge will create an abrupt transition, while a brush with a soft edge will gradually fade by adding gray to the image, which is semi-transparent.
While the brush tool is often the most helpful, you can also use:
- The paint bucket tool. Use the paint bucket to make the entire layer black instead of white. This way, you can paint the object white instead of painting the entire background black.
- The gradient tool. Because white shows and black is excluded, a black and white gradient can apply a subtle transition to an adjustment layer.
Use those tools until you have selected the areas of the photo that you want selected.
5. Fine-tune the layer mask.
Photoshop offers more than just a brush tool to make selections within that layer mask. Inside the Properties panel, click the layer mask icon to adjust the properties of the layer mask. (If you don’t see the properties window, go to Window > Properties.)
Here, you can feather the mask for a softer edge. Adjusting the density of the layer mask will lighten those black layers to gray, bringing those areas back in just a bit.
Under the refine options you can access the Select and Mask workspace, which tends to be an easier way to adjust a mask around fine details like hair. You can also refine the selection by color range, or invert the selection.
From here, continue editing your photo. You can go back and adjust a layer mask at any time to add or subtract more of the selection. To go back to your layer mask, simply click on the mask in the layers panel and continue to fine-tune.
This was a basic overview of how to get started with Photoshop layer masks. How you use them depends on entirely on what you want to do. Layer masks are infinitely adjustable, and when combined with adjustment layers, allow for a flexible, non-destructive way to edit photos. Sometimes, just playing around with different selection tools, paint brushes, and gradients can reveal new ways to use layer masks that you may not have thought of, so don’t be afraid to experiment.
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