Quick Tip: Layer Mask vs. the Eraser Tool in Adobe Photoshop

Final product image
What You'll Be Creating

In many of my tutorials you may find a command: "Remove the part using a Layer Mask or simply the Eraser Tool". As a beginner, you might react to it by selecting the Eraser Tool because you're familiar with it, and a Layer Mask sounds like some professional technique.
The truth is that using a Layer Mask is not much different from using the Eraser Tool, but it gives you more possibilities. It saves you a lot of time and it gives you flexibility. The only advantage of the Eraser Tool is that it's a substitute for the "real thing" that you're already familiar with. But why would you limit yourself to substitutes for traditional tools when working digitally?
Try this quick tutorial to see how you can use Photoshop and its digital tools to your advantage. Discover a new type of eraser, a non-destructive one, that lets you bring back things you've erased before without any loss!
Let's see a very simple situation in which you could use the Eraser Tool. You have sketched a snow leopard:

drawing eraser mistake

You've got a feeling the tail is a bit too long, so you use the Eraser Tool (E) to remove the tip.

drawing eraser mistake how to reverse

Now it feels wrong, so you do your research and it turns out that snow leopards do actually have disproportionately long tails. You can now do three things to fix your "fixing":
  • Use the Undo command (Control-Z) as many times as needed to get back to the previous state.
  • Close the file without saving your last changes, and open it once again to see the previous state.
  • Redraw the previous state.
The first solution works great if you have enough history states (the more of them you keep, the slower Photoshop may work), and if you didn't do anything importantafter erasing the tail. The second solution works only if you have saved right before erasing—not much earlier or somewhere during it. And the third solution wastes your time.
If you used a Layer Mask instead, you could even remove a great part of the tail, like this:

drawing eraser mistake how to reverse layer mask photoshop

And then you could use an "anti-eraser" to bring back any of the parts, even after closing the file and opening it once again!

drawing eraser mistake how to reverse layer mask parts
drawing eraser mistake how to reverse layer mask anti eraser

Looks like magic, doesn't it? Let's see how to achieve it!
You can download this file as the attachment to follow my steps:

photoshop layer mask file

We attach Layer Masks to particular layers. Select the one you want to add a Layer mask to.

photoshop layer mask select

Click Add Layer Mask.

photoshop layer mask add

A white thumbnail should appear to the right of the main one:

photoshop layer mask added

Notice that you can select both thumbnails. It's very important to pay attention to which one is selected, because they are like two layers placed at the same level. If you draw something on this layer, you'll affect the thumbnail that's been selected.

photoshop layer mask select mask layer

Make sure that the mask is selected. Pick a brush of your choice and draw a big black dot right in the middle of the leopard's body.

photoshop layer mask black transparent

See what happened? When the mask's thumbnail is selected and you draw something black, you actually select the parts of the main image (the layer you're working on) that you want transparent.

photoshop layer mask black effect

Now switch to white. Draw a white dot inside.

photoshop layer mask white opaque

This part came back! This is our anti-eraser.

photoshop layer mask white effect

For now you see only the effects of the mask. To see the mask directly, press \. The red parts symbolize full black.

photoshop layer mask red selection

To get your original image back, simply take a big white brush and paint on the mask.

photoshop layer mask how to clear mask

As we've noticed, white defines opaque parts, and black transparent. You can also use grays—the darker the shade, the greater the opacity of that part.

photoshop layer mask gray opacity
photoshop layer mask gray effects

Let's use this technique to hide the leopard's paws deep in the snow. Select the mask, take a soft brush, and paint the paws with black.

photoshop layer mask soft brush
photoshop layer mask soft brush effect

You can use any brush you want, and mix them for a proper effect:

photoshop layer mask mixing brushes

When you right-click the mask, you get a list of options. Only the first three of them interest us:
  1. Disable Layer Mask—turns off the effects of the mask, so that you can see the original image. You can enable it any time.
  2. Delete Layer Mask—removes the mask entirely, leaving the original image unaffected.
  3. Apply Layer Mask—merges the effects of the mask into the image. The mask is then removed, and the original is permanently changed.

photoshop layer mask options

If you want to copy the masked image, you need to hide all the other layers and useCopy Merged (Control-Shift-C). If you use a normal way of copying, you'll copy the original image instead.

photoshop layer mask select copy

Even though it's such a great tool, a Layer Mask shouldn't be used every time you want to remove a part of the image. When you're sketching, the Eraser Tool is much faster and more effective. If you combine it with constant copying of the layer you're working on, you'll also have a lot of back-ups to come back to.
Layer Masks are much more useful for photos and digital painting, where you have big areas of the image to work on.
You can use Layer Masks to create a soft blending between images. In contrast to the Eraser Tool, with a Layer Mask you get countless chances to adjust the blending.

photoshop layer mask blend soft

When you apply a photo texture to an object, you may want to use only parts of it. By using a Layer Mask you can easily remove the texture from the parts where it's undesired.

photoshop layer mask texture apply parts
Paint Foxy From the Five Nights at Freddy's Series in Adobe Photoshop

Beginners often paint light and shadow separately, but the truth is that shadow is only lack of light. In digital painting you can first cover all the scene with the shadow, and then illuminate some parts (remove shadow) by painting them on a Layer Mask.

photoshop layer mask light shadow

You can also notice that Adjustment Layers have their own Layer Masks by default. You can use the same mechanism to apply the adjustment only to parts of the picture.

photoshop layer mask adjustment apply part
photoshop layer mask adjustment effect

Photoshop has a lot of tools that are not obvious to use, but once you find them, they prove to be incredibly useful and more effective than their more intuitive counterparts. The Layer Mask is one of them, but I'm sure it's not magic for you any more!


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