Photoshop: Beginner’s Guide to Masking

Learn all about masking and why it is such an awesome feature of Photoshop (and basically every creative app out there!) and how to create masks from scratch and from selections in Photoshop.

Use masking to selectively change colors in your image

It’s much easier to show how a mask works than to explain it. So I’ll try to first show you and then explain it all. To see it in action, let’s load up a selection that I saved. This selection is of the colored part of this train on the left as we have here. This selection has been refined and feathered a little so hopefully, it will look pretty good once we change this color.

When you have an active selection like this and you create a new adjustment layer, Photoshop will automatically create a mask that constrains the adjustment you make to only the area you have selected. In this case, we want to change the colored stripe on this train so we’ve selected the color and now we’re going to use a Color Fill layer to add a new color. I’m going to choose a nice middle blue. The hex code is #1e5074. Hit OK and you can see how the color is only affecting that part of the train (the part that we had selected).

This is how a mask works. It creates a black mask over the layer it’s attached to and the holes you cut in the mask, by painting with white (or in our case, by filling a selection with white) will allow the contents of that layer to “show through.” The content of this layer is simply the color blue. You could use a mask exactly like this on a regular layer that you have just filled with any color you like as well. We’re using a Color Fill layer because they’re more flexible and it makes me look more like a pro to some of the people who watch this video.

Adobe Stock used in this tutorial:

The paint job looks terrible because it’s not blended into the metal of the train, so we can change the blend mode of this layer to “Color” and you can see how effective a mask is at containing a color change to one specific area.

But wait a minute! The client just sent me an email and they want both trains to have this new blue color paint job. With a mask this is easy. We will grab our paintbrush tool and use a nice soft-edged brush to paint white in the mask to allow the blue color to fall on the orange train. NOTE: Whenever you look at a layer with a mask attached to it in your layers panel, you’ll see that there is a white outline either around the layer thumbnail or the mask. This indicates whether you’ve selected the layer contents or the mask. Because we want to use our paintbrush on the mask, we want to make sure we click the mask that belongs to this layer in the layers panel. Now begin painting with white and you’ll see how easy it is to spread this color change across to the other train.

The power of masks is in the fact that you can come back anytime, any day, and add or remove from this mask with ease. But the power of masks is not only in the fact that it’s such a non-destructive option.

Masks are also great because they allow you to quickly and intuitively blend and re-blend adjustments when you’re editing your images.

Blending in a new sky

To show this blending idea, let’s shift focus to this image of a deer. We want to add a sky so we will drag in any old image of a sky and find a blend mode that works well. In this case, I went with Soft Light. Now we add a layer mask to this layer by hitting the layer mask icon. Notice a fresh mask is white and empty. As you can see, nothing has changed because a white mask is hiding nothing. We need to add some black paint to the mask to cover the sky.

Let’s hide the whole thing by filling the mask with black. Select the mask in the layers panel and then go Edit>Fill and choose to fill with Black. FUN TIP: You can hold down your Alt/Opt key when clicking the new mask icon to create a new mask that is already filled with black. Now grab the brush tool and we’ll use a big, soft edged brush set to 40% opacity and dab in clouds by painting white on our mask. Again, be sure you’ve selected the mask before you begin painting.

The soft edges on our brush will create a smooth blend as we dab away to place and blend the clouds into the sky of this image. You can spend as much time as you like dabbing with white to reveal clouds FUN TIP: Tap the letter X to flip your foreground and background colors and then dab with black to “paint away” clouds where you don’t want them. Ahh, the beauty of masks. Just a side note here, I reduced the opacity of the brush tool and this helps immensely with controlling how this blending process goes. I’d rather clickity click a bunch of times than click once and realize it’s all a disaster.

By the way, if you’re curious about what this masked sky looks like without that Soft Light blend mode making it half-invisible, check it out when I set it back to the Normal blending mode. Pretty cool. I’m going to set that back to Soft Light for now.

The next thing doesn’t really fall within the scope of this tutorial, but I will also add a Color Lookup Table adjustment layer and use the “Drop Blue” LUT and then reduce the opacity of this layer to 70%

Use masking to quickly adjust specific areas of your image

Next, let’s say you’re working on retouching a lookbook fashion shoot for the client, but they say they want to switch the yellow stripes to pink on this woman’s shirt. Add a Hue/Saturation adjustment layer. Target the Yellows and swing the hue until it looks right. Ignore the rest of the image, we have masking to do!
Select the mask in the layers panel and hit Cmd/Ctrl + I to invert the mask, swapping the white to black. Grab the brush tool and set it back to 100% opacity and quickly paint in the shirt area to complete the task. Boom. Done. Easy work. FUN TIP: You can Alt/Opt + click on the mask to view the alpha channel and see it in black and white. Do this and touch up areas of the shirt that you know should be solid white.

Use masking to get rid of a background or cut out an object

Masks are great for any time you want to erase part of something. Erase a sky, erase a background, erase the color blue everywhere maybe except on our trains in that picture, or even erase the bits of the sky we don’t want.

Anyway, moving on from that ridiculous digression, we can load a selection of this guy using the “Select Subject” button because he’s well-focused and on a simple background so we can be confident that the selection will be pretty good.

Next, we can choose “Select and Mask” and add a tiny bit of feathering to the edges of the selection–and make any other changes to your selection in here–and choose to output the selection to a Layer Mask. Hit OK and you will see that we have masked away all of that background and revealed our image behind him.
FUN TIP: you can also create a selection around your model and bypass tweaking the selection and simply hit the new mask icon at the bottom of the Layers panel. This will keep visible whatever you have selected and hide everything else, but the edges of your selection might not be as good as they could have been.

I’ll convert this whole thing to black and white with a little blending just to make things fair and I’ll leave you with a couple of tips you can use when you’re working with masks in Photoshop:
Shift + click a mask to temporarily hide the mask.
Click and drag the mask to the trash can to delete the mask.
Alt/Opt + drag the mask up to a new layer to copy that mask to another layer.
Right-click the mask to get a menu of options regarding things you can do to or with that mask such as deleting the mask, applying the mask to the layer, entering Refine Mask mode, and more.

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