Understanding Layers & Masks in Photoshop

Layers and Masks are two of the most important functions that you find in Adobe Photoshop. It’s among the many things that make it a great tool for those who want more flexibility with post-processing than what you get in Lightroom or other RAW editors.

With Photoshop the possibilities are almost endless so it’s easy to understand that it is overwhelming in the beginning. Perhaps you’re in that state right now; wanting to step up your processing but Photoshop seems so complicated that you feel like giving up.

Don’t worry though… It might take some practice and a lot of trial and error but it’s worth it.

Layers and Masks are two things that can be confusing in the beginning. However, they are crucial to understand to fully take advantage of Photoshop. These two tools give you full creative control and are what you need to use if you want to step up your image editing skills.

Keep reading and, hopefully, you’ll learn that they aren’t quite as scary as they first seem:

What are Layers in Photoshop?

So, what exactly are layers, and why are these so important to understand?

Layers are Photoshop’s way of displaying the hierarchy of images or adjustments. Just as with a cake, only the top layer is visible but all other layers are essential in both consistency and taste.

This means that if we have three layers in Photoshop, the bottom is blue, the second is red and the third is green, you’re looking at a green image. Why? Because the green layer is on top.

When you add one layer on top of another, the top layer will be the one that’s visible. In other words, if you re-arrange the layers and place the red layer on top instead, the image is red. Erasing part of the top layer will reveal the layer below in the erased area.

Editing Images with Adjustment Layers in Photoshop

While the explanation above gives you a general idea of what layers in Photoshop are, you’ll quickly learn that they are used a little differently for post-processing.

Rather than only working with solid layers, we rely more on what we call Adjustment Layers. These layers are transparent until you change the apply the accompanying adjustment.

The Curves Adjustment Layer is a good example. Nothing actually happens to the image when you open this adjustment (Create New Fill or Adjustment Layer -> Curves).

The image remains the same and the new layer appears to be invisible. When you make an adjustment using the Curves tool, however, the adjustment becomes visible. If you then proceed by creating another Adjustment Layer, for example, Photo Filter, the curves adjustment remains visible and the new will be added on top of it.

This type of workflow where you mostly rely on Adjustment Layers is known as a non-destructive workflow. That means a workshop where you can go back and make an adjustment to any of the Adjustment Layers (no matter where they are in the hierarchy) and the change will be visible.

This won’t be possible if you’re working with solid layers instead of Adjustment Layers. A solid layer can be thought of as another image that covers the entire frame. A new solid layer is essentially putting a new image on top of the hierarchy, not allowing you to make changes to any of the previous adjustments.

That’s where masks can help.

What are Layer Masks in Photoshop?

Layer Masks, normally just referred to as masks, are the second essential feature in Photoshop. It can help you in the “solid layer” situation above but also let you do what’s known as selective editing.

You now know that the top layer is always at the top of the hierarchy and when solid, it conceals the layers beneath. If you want to remove an adjustment from a specific area, you could use the erase brush directly on the layer but this isn’t a good solution. A better option is to apply a Layer Mask.

The Layer Mask appears as a white rectangular box that’s shown next to the layer in the Layer Panel. It’s white by default but can represent two true colors: black and white, plus the shades of gray in between.

A white Layer Mask means that the entire layer/adjustment is visible. A black Layer Mask is the opposite and hides the layer and its adjustments.

Remember this phrase: White Reveals and Black Conceals

Let’s take a big step back and look at the scenario where we had a blue, a red, and a green layer. In that example, I used the erase brush on the green layer to reveal the red layer beneath.

The problem with doing this is that we aren’t able to recover the erased part if we need to. You have to do it to perfection the first time and know that you’ll never need that area again.

A better way of doing it is to apply a layer mask to the green layer. As mentioned, the mask is white by default which means that the top layer is shown in its whole.

You can then select the Brush Tool (B), change the foreground color to black, and change to a suitable brush size. Now, make sure the Layer Mask is selected (click on it) and paint on the image. As you do this, you’ll see that the red layer becomes visible in the areas you’re painting.

Note: If the image is becoming black where you painted, you haven’t selected the Layer Mask. Click on the Layer Mask and make sure there’s a white frame around its icon.

Take note that the Layer Mask also changed; the areas you painted onto have now become black. Once again, I’ll repeat the phrase White Reveals, Black Conceals. What this means is that we can use the Layer Mask to apply selective adjustments. Adjustments that are only applied to specific parts of the image. This is something that’s going to be a game-changer for your image editing. It gives you full control.

Layer Masks have several benefits and, personally, I use them in almost every single layer I create when processing an image in Photoshop. Here are some of the scenarios where I use a Layer Mask:

• When adjusting the color balance to a specific tonal range (such as adding blues in the shadows)
• For blending multiple images together
• Removing an adjustment from an area I want untouched.

The Challenges of Layer Masks

Regardless of how useful Layer Masks will be for your performance in Photoshop, it’s important to understand that they aren’t perfect right away. Just painting with a brush on the Layer Mask is fine in many scenarios but it often results in haloing.

Since you’re manually painting on the mask, it’s easy to get a little sloppy and paint slightly above the edge or outside the area you want to reveal or conceal. This often becomes a problem as it’s a very visible mistake.

Instead of just painting with the brush (though it’s completely fine in certain scenarios), I recommend learning how to use Luminosity Masks. You’ll want to first learn the basics of Photoshop but this will be the next step as you can create extremely precise selections for your mask.

An example of when Luminosity Masks are beneficial is when you want to make a targeted adjustment. I often adjust the color balance in certain areas of the image. For example, I might add a little blue in the darkest shadows. Luminosity Masks help me create a selection that only targets the darkest shadows. When painting onto the mask with this selection, I don’t have to worry about brushing into an area I don’t want to be affected.

Conclusion

Layers and Masks are two of the most important tools a photographer will use in Photoshop. Being able to selectively apply adjustments is something that will take your photo editing skills to the next level.

I know that Layers and Layer Masks sound a little confusing if you’ve just opened Photoshop for the first time but I encourage you to spend some time playing around with them.

These are essential in your use of Photoshop and you won’t be able to properly benefit from this software unless you understand them.

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