Anyway, I thought I’d summarize what I shared here because sometimes folks like the abbreviated version.
Basically, after a mask is applied to a layer in Photoshop, there are two thumbnails for that particular layer in the Layers panel. The first thumbnail, the one on the left, represents the image itself. The pixel based content. The thumbnail on the right represents the layer mask. The thumbnail on the left should look like the image and the one on the right should look black and white. During the process of editing and working on an image, it’s common to jump between these two thumbnails. Typically, for newer editors who aren’t all too familiar with the keyboard shortcuts that are assigned to functions in Photoshop yet, clicking each thumbnail with the mouse pointer is common. For those more experienced, using the following keyboard shortcuts is common.
To select the pixel based thumbnail: Ctrl (Command)+2
To select the layer mask thumbnail: Ctrl (Command)+\
Using these two shortcuts will allow you to jump back and forth between the two thumbnails quickly and easily.
Separating Layers & Masks
Under certain circumstances, it may become necessary to separate a mask that’s been created from the pixel based portion of the layer. To separate the mask from the pixels, simply click once on the small lock (chain) icon that’s located directly between the two thumbnails in the Layers panel. To reconnect these two portions of the layer, click in the same spot again.
Concealing & Revealing
You may already be familiar with masking basics, but I’ll still cover this portion of masking here. If you’d like to hide and show portions of an image, a layer mask needs to be first applied to the layer in question. Then, when the pixel based thumbnail is selected, you can use the Brush Tool to paint black on the areas you’d like to hide and white on the areas you’d like to show. If you choose a gray color, the result would be similar to those where opacity was reduced.
Turning a Layer Mask Off
If you’ve got a layer mask already applied to a layer and would like to turn it off so it doesn’t show its effects any longer, you can hide it from view, or disable it. To disable the mask, simply hold down the Shift key on your keyboard and then click on the mask thumbnail.
Removing a Layer Mask
If you’d like to remove a layer mask in its entirety, you can do that as well. Click the mask thumbnail in the Layers panel and then drag it down to the trash can at the bottom of the panel. Then, click the Delete button in the box that pops up. If you click on the Apply button, the mask effect will become permanent before the mask is deleted.
If you’d like to view a fully functional life-size view of the layer mask in black and white, as an overlay on the image itself in the workspace, hold down the Alt (Option) button on your keyboard and click once on the layer mask thumbnail in the Layers panel. To view the mask as a semi-transparent red overlay as opposed to the black and white, hold down the Shift+Alt (Option) keys on your keyboard and do the same thing. To hide the overlay, simply use the same keys to reverse the procedure.
I think that’s all for now. Again, if you’d like to see the full post with screenshots and everything, click the links at the top of this post. Also, let me know if you have any questions down below. Thanks!