To invert a mask in Photoshop, it's a super simple process. I'll walk you through it right now.
First, I'll open a photo in Photoshop. That photo will be the only layer in the
Layers panel. I'll click on the small lock icon in that layer to unlock it. I'll also right-click on the thumbnail in the layer and choose
Large Thumbnails in the menu that appears. Here's what that looks like.
The reason I do this is because I like to see what I'm doing when I work with masks. If the thumbnail is too small, I can't see anything.
Okay, next, I'll head down to the bottom of the Layers panel and I'll click the
Add Layer Mask button. Once I do that, the layer mask will appear in the layer right next to the photo thumbnail.
The mask is the white box to the right of the image thumbnail.
At this point, since I've got the mask in place, I can work with it. For this example, I'll use the
Brush Tool to paint the middle of the picture black. I'll set the color picker to black before I do this, obviously. Also, before I paint, I'll make sure to click on the white mask box that's in the Layers panel.
Before I continue, I want to remind you of one thing. When you paint a mask black, whatever it is in the photo or layer that you're painting will disappear. In this case, it'll become translucent because I've got no other layers. If I had a layer of something underneath this one I'm currently working on, that bottom layer would show through. So by painting with black in a mask, it's almost as if you're erasing the layer you're working on. If I were to switch over to white and paint with that, whatever I just made disappear would reappear again. Black conceals and white reveals. The benefit of working with masks as opposed to using the
Eraser Tool is that the Eraser Tool removes pixels permanently while masks don't. You can always get the pixels you hide back when working with masks. This is considered to be
non-destructive. The Eraser Tool is
destructive.
Moving on. I'll go ahead and paint with black over the mask. Check it out.
Let's see what that looks like in the Layers panel. You can see the black squiggly line in the white mask thumbnail.
Now for the good part. If I wanted to reverse this, or invert the mask, all I'd have to do is head up to the
Image > Adjustments > Invert menu item and click. Again, the mask in the Layers panel will need to be active, so I'll click on that, just to make sure.
Let's take a look at the image now.
Do you see how it's been inverted? Let's also take a look at the mask thumbnail in the Layers panel.
See how that's been inverted as well? It's that simple. And if you wanted to do this very quickly, you can use the keyboard shortcut of
Ctrl+I. That's for Windows. I'm assuming the same shortcut is
Command+I for Mac. If inverting the mask with the keyboard shortcut doesn't work for you, make sure the mask thumbnail in the Layers panel is selected. Otherwise, you'll be adding a blend mode to the image itself and that's not what you want.
