What a layer mask does and why you need one

A layer mask in Photoshop lets you hide or show parts of a layer without deleting anything. Instead of erasing pixels permanently, you paint black on the mask to hide, white to reveal, and gray for transparency in between. The original image stays intact — you can always undo the mask or paint it back in later.

This matters because it gives you control that deletion does not. You can blend two photos together, fade an image into a background, remove a person from a photo without leaving a hole, or create complex compositions where layers fade in and out. If you change your mind about what should be hidden, the pixels are still there.

Key Takeaways

  • Right-click any layer and choose "Add Layer Mask" to create a mask; start with "White (Full Opacity)" if you want to hide parts by painting black.
  • Paint with black on the mask to hide that part of the layer, white to reveal it, and gray for partial transparency.
  • The mask itself is separate from the image — you can edit the mask and the image independently by clicking the right thumbnail in the Layers panel.
  • Use the Brush tool with soft edges and lower opacity to create smooth fades and blends instead of hard lines.
  • Refine your mask later by painting over it again, adjusting levels, or using Photoshop's mask refinement tools without touching the original photo.

Adding a mask to a layer

Open your image in Photoshop and look at the Layers panel on the right side of the screen. Click the layer you want to mask. Right-click on that layer name and select "Add Layer Mask" from the menu that appears.

A dialog box opens with three options. Choose "White (Full Opacity)" if you plan to paint black on the mask to hide parts of the layer — this is the most common starting point. Choose "Black (Full Opacity)" if you want the entire layer hidden and plan to paint white to reveal it. Choose "Layer Mask from Transparency" only if your layer already has transparent areas you want to convert into a mask.

Click "Add" and Photoshop creates a white rectangle next to your layer thumbnail in the Layers panel. That white rectangle is your mask. The layer thumbnail (the image) stays on the left; the mask thumbnail appears on the right with a white border around it, showing the mask is now active and ready to edit.

Painting on the mask to hide and reveal

Select the Brush tool from the toolbar on the left. In the tool options at the top, set your brush opacity to 100% to start — you can lower it later for softer fades. Make sure your foreground color is black (press D on your keyboard to reset to default black and white).

Paint on the image where you want to hide the layer. As you paint black on the mask, those parts of the layer disappear, revealing whatever is underneath — another layer, the background, or transparency. The image itself never changes; only the mask records where you painted.

To reveal parts again, switch your foreground color to white (press X to swap foreground and background colors) and paint over the hidden areas. To create a smooth fade instead of a hard edge, lower your brush opacity to 30–50% and paint along the edge where you want the transition to happen. Gray on the mask creates partial transparency, so the layer shows through faintly.

Working with soft edges and opacity

Hard-edged masks look unnatural in most photos. Before you start painting, adjust your brush settings. In the Brush panel (Window > Brush if it is not visible), choose a soft round brush — the default brushes include several. In the tool options bar, set Hardness to 0% for the softest edge possible.

Lower your opacity to 30–50% instead of 100%. This lets you build up the mask gradually, creating smooth transitions. Paint once over an edge and it fades slightly; paint again and it fades more. This gives you control over how gradual the blend is.

If you make a mistake, paint with white to undo it, or press Ctrl+Z (Windows) or Command+Z (Mac) to step back. There is no penalty for painting over the mask multiple times — you are only editing the mask, not the photo.

Editing the mask separately from the image

In the Layers panel, you will see two thumbnails side by side for your masked layer. The left thumbnail is the image; the right is the mask. A white border appears around whichever one is active. Click the mask thumbnail (the right one) to edit the mask. Click the image thumbnail (the left one) to edit the photo itself.

This separation is powerful. You can adjust the image's color or brightness without changing the mask, or refine the mask without touching the photo. If you paint on the image by mistake, undo and click the mask thumbnail to switch back.

To see only the mask (useful for checking your work), hold Alt (Windows) or Option (Mac) and click the mask thumbnail. The canvas shows the mask in grayscale — white areas are fully visible, black areas are hidden, and gray areas are semi-transparent. Click the thumbnail again while holding Alt or Option to return to normal view.

Refining and adjusting your mask

After you paint a mask, you can adjust it without repainting. Click the mask thumbnail to make sure it is active, then go to Image > Adjustments > Levels. Drag the middle slider left to make the mask more transparent overall, or right to make it more opaque. This is useful if your fade is too subtle or too harsh.

You can also use the Eraser tool on the mask (with the mask active) to soften edges further, or the Dodge and Burn tools to lighten or darken specific areas of the mask. Every edit is reversible — if you do not like the change, undo it or paint over it.

If you want to start over, right-click the mask thumbnail and choose "Delete Layer Mask." The layer returns to its original state with no mask. You can add a new one and try again.

Common uses for layer masks

Blending two photos: Place one image on top of another as a separate layer. Add a mask to the top layer and paint black along the edges to fade it into the layer below. This creates a smooth transition between two images without visible seams.

Removing a person or object: Place a clean background layer underneath. Add a mask to the layer with the unwanted object and paint black over just that object. The background shows through where you painted, making the object disappear.

Creating a vignette: Add a mask to your image layer. Paint black around the edges with a very soft brush to darken the corners and draw attention to the center. Adjust opacity to control how strong the effect is.

Selective adjustments: Create an adjustment layer (like Curves or Hue/Saturation) and its mask automatically appears. Paint black on the mask to limit the adjustment to only certain parts of the image — for example, brighten just the sky without affecting the ground.

Frequently Asked Questions

Can I copy a mask from one layer to another?

Yes. Right-click the mask thumbnail on the layer with the mask you want to copy and select "Copy Layer Mask." Then right-click the destination layer and choose "Paste Layer Mask." Photoshop pastes the exact same mask pattern onto the new layer.

What if I paint on the mask and nothing happens?

Check that the mask thumbnail (not the image thumbnail) has a white border around it in the Layers panel. If the image thumbnail is active, you are painting on the photo instead of the mask. Click the mask thumbnail to switch. Also make sure your foreground color is black or white, not another color — masks only respond to grayscale.

Can I use a layer mask on a background layer?

No. Photoshop does not allow masks on background layers. Right-click the background layer and choose "Convert to Layer" first. It becomes a regular layer and you can add a mask to it.

How do I make the mask permanent so I cannot undo it later?

Right-click the mask thumbnail and choose "explore Layer Mask." Photoshop converts the mask into actual transparency on the layer — the hidden pixels are gone and cannot be recovered. Only do this when you are certain the mask is final.

Can I use a selection to create a mask instead of painting?

Yes. Make a selection using the Lasso, Magic Wand, or Select Subject tool. Then right-click the layer and choose "Add Layer Mask." Select "Selection" in the dialog. Photoshop creates a mask based on your selection — the selected area is white (visible) and everything outside is black (hidden).