Layer masks are grayscale images that show or hide areas of the layers to which they have been applied. The gray tones on the mask reflect the transparency of corresponding areas on the layer: black areas are completely transparent and, therefore, invisible; white areas are not transparent at all, so they're completely visible; and shades of gray have varying degrees of transparency, depending on how dark the gray is (the closer it is to black, the more transparent the corresponding section on the image layer will be).
You can edit a layer mask using any of the drawing or painting tools, including the pencil and brush tools (B), the Gradient Tool (C), and the Paint Bucket Tool (C). Drawing on a mask affects the mask only, and does not touch the pixels that make up the image. Draw or paint on the mask in black, white, or gray.
In this solution, I used a black-to-transparent gradient to create a gradient on the layer mask. This allowed the upper part of the image to remain visible, but let the lower part fade away so that the background color could show through.
We could also have created a fade effect with the Brush Tool (B). In the example shown, I've selected a soft-edged brush, set my foreground color to black, and painted along the bottom of the image on the layer mask to paint out the areas I want to fade.
You're probably wondering why you wouldn't just paint a green gradient on the bottom of the picture layer, or on its own layer, to achieve the same effect. Why use a layer mask?
The beauty of layer masks is that they are non-destructive. They don't actually modify any of the pixels on the image layer itself—a benefit that, ultimately, gives you greater flexibility. If you decided that you didn't want the effects you'd created using your layer mask, you could get rid of the mask and the original image would remain intact. Or, if you decided you didn't like the green color, you could change the background color and the fade effect would still work.
Was this article helpful?