Tip - how to use a layer mask

A short tip on layer masks. Hide part of a layer with black paint and bring it back with white, without erasing anything. Free in your browser with PhotoFresco.

Say you put a night sky over a daytime harbour and want the harbour to show through at the bottom. If you erase the sky, it is gone. A layer mask does the same job without deleting anything: white on the mask shows the layer, black hides it, and you can change your mind at any time.

Add and paint a mask

  1. Open a picture in the editor and add a second one on top with File ▸ Import ▸ Image as Layer….
  2. With the top layer selected, choose Layer ▸ Layer Mask ▸ Add. A white box appears next to the layer's picture in the Layers panel. Click it so it has an outline: that is the box you paint on.
The Layers panel after adding a layer mask: a white box next to the top layer
The Layers panel after adding a layer mask: a white box next to the top layer
  1. Choose the Brush (B). In the bar at the top set Hard to 0 for a soft edge and Size to something large. Make sure the colour is black.
  2. Paint over the part you want to hide. It disappears from the picture, and the mask box turns black in that place.
  3. Painted too much? Press X to swap black and white, and paint over it again to bring it back.
A night sky fading into a harbour: the mask shows black where the lower picture comes through
A night sky fading into a harbour: the mask shows black where the lower picture comes through

Good to know

  • The Gradient tool paints the layer's own pixels, not the mask, in this version. Use the Brush for masks.
  • To cut a subject out of a plain background, make a selection first and then add the mask. See How to remove the background from an image.
  • Save a PSD (File ▸ Save As…) to keep the mask editable.

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