There are a thousand ways to create a layer mask in Photoshop. Many of them will yield a gray-scale mask with many shades of gray, and it can be a bit difficult to get the contrast of such a mask just right so that you have solid black where you want to hide the layer and solid white where you want to reveal it.
In this excerpt from my Mask It Like a Pro! video course, I will show a neat little trick that allows you to get the perfect mask in such cases. I am using the Brush tool with Black and White as the color. The trick here is to set the mode of the brush to Overlay.
Check out how this works in detail.
In a Nutshell…
Our goal in this particular case is to create a layer mask that reveals only the clouds in the sky and hides the blue parts. The original mask has a very noticeable fall-off in brightness to one side. By using the Brush tool in Overlay mode, we can gradually darken the darker parts and brighten the brighter parts in places where this is needed. What we will end up with is a very good mask that only reveals the clouds, as intended.
- Activate the Brush tool.
- Choose Overlay as your Mode.
- Press ‘D’ on your keyboard to set the foreground color to White and the background color to Black.
- Set the Flow to around 5%.
- Brush repeatedly on the dark parts with Black and on the bright parts with White. This will darken the dark regions and brighten the lighter regions, and this effectively changes the contrast. You can use the ‘X’ key to switch between Black and White as the foreground color quickly.