Today, we are going to look at two of the main Clipping Masks techniques in Photoshop. Layer masks and clipping masks. We are going to compare the two by looking at how they work on a practical level, the most significant basic similarities, and differences.
Lastly, we will see how we can get the two types of skins to work together in a design.
I know a lot of people find clipping masks a bit strange, but I’ll try to make it as simple and as painless as possible. So let’s get to it.
About the masks
First, we are going to establish a working definition of what a mask is. Basically, a mask is an entity that controls the behavior of a collection of pixels. Generally speaking, this control focuses on the relative transparency or opacity of a layer or group of layers.
Whenever a mask is active or “on”, a pixel becomes transparent. In case a mask is inactive or “off”, a pixel remains opaque. On the other hand, a mask can be active or inactive to different degrees, allowing a wide range of transparencies.
When combined with Photoshop’s ability to stack different layers, masks become an incredibly powerful tool, helping to grant a digital designer or artist very precise control over the interaction between different layers. For example, we are going to take advantage of this beautiful image that I took in Dreamstime.
Now we are supposed to want to extract from the woman from the bottom. To achieve this, we can start by using any of a number of different extraction methods (in this case, I used the channels, which could make another full article). However, instead of removing the unwanted pixels, I’ll just hide them with a mask.
The missing pixels were not erased. They are simply invisible now. Now, the woman can be placed in a completely different plane, which I have created using some textures from some texture packs, which you can consult here and here.
So that’s the basic concept of masks. Now let’s take a look at the layer mask and the clipping mask and how they each accomplish this same basic premise.
The layer mask
A layer mask is a “one-to-one” masking technique, I mean a single mask is applied to a single layer. It is possible to replicate a layer mask and apply the copies to other layers, each layer, but ultimately still has its own mask.
Layer masks also exist strictly as masks and have no other explicit purpose. They are a way to control the transparency and opacity of a single layer, but they don’t do much beyond that.
To create a layer mask, open the layers palette and select the layer you want to work with. Then click the mask button ( ) to create a new blank mask.
If you do this with a selection active, the selected pixels will be set to visible while the unselected pixels will be set to transparent. Partially selected pixels will be transparent in direct relation to the degree of your selection.
In our previous example – we extracted the woman from the dark background – I have used a layer mask. Here is a screenshot of my layers palette.
Notice how the thumbnail image of the mask layer is in black and white and appears next to the layer thumbnail (or the icon, if you have your palette set to show the icons). This is a great visual representation of how the layer mask is connected directly to the layer itself.
This preview also gives you some useful functionality, as we are on the subject. Try pressing Command (PC: Ctrl-click) to create a new selection based on the mask, similar to the way you create a selection from a channel.
You can also Shift + click on the preview to quickly toggle the mask between “preview mode” and “mask mode”, to edit the mask itself or just the image. You can also type “Option” (PC: Alt + click) to toggle between preview mode and skin mode, in which you can view and edit the skin itself instead of the active preview of its effect.
The clipping mask, on the other hand, is something else entirely. As we can think of the layer mask working as a one-to-one type entity, the clipping mask functions are more like a one-to-many type entity as it can actually affect multiple layers at once .
A clipping mask is also, by its very nature, multi-purpose. Since the layer mask is a modification to a layer, a clipping mask is actually a layer, interacting with one or more of the layers directly above it. This has some interesting implications, which we will get to shortly.
Personally, I still find creating clipping masks quite counter-intuitive. First, select the layer you want to mask. If you want to have multiple masked layers, select the layers you want (all must be in direct sequence). Right-click and select “Create Clipping Mask” from the context menu, see what happens.
All selected layers are indented and masked by the first layer immediately below them. Maybe it’s just me, but this seems so weird. I always want to create the mask by clicking on the layer that I want to make the mask (which is the first layer below the dashes), although I understand why that would be a programming problem. However, I have gotten used to it over time.
Here is a practical example. Suppose we want to “insert” the entire photograph into a vector frame. The easiest way to do this in Photoshop is by using a clipping mask! First, open your vector file and import it into Photoshop. There are several ways to do this, but generally, I choose to import as a smart object.
I opted to use an ink splatter in a vector shape. I have combined several different shapes of Franz Ghori’s Spray Paints, (which I downloaded from Vecteezy) to create these splatters.
With this shape inside the document, I can simply activate my photo and drag it directly on top of my new shape layer. Then you just right click and create a clipping mask. Immediately the photograph is cropped by the shape of the mask.
It is that easy. Now, if you wanted, you could either select and move the photo itself or the cropping shape, and the mask was immediately updated. In fact, you can also see the mask change as you make modifications to either of these two layers.
Pixel Controls Pixel controls
One of the key differences I want to focus on is the way masks work, the way they control the transparency of the masked pixels. It is important to understand this difference as it will have an impact on the way your skins are created.
The layer mask is based entirely on a grayscale image. In a sense, the layer mask is a grayscale image, which is superimposed on the actual pixels of the layer itself, and is used to calculate the effects of the mask.
The relative darkness or white is what controls the behavior of the pixels. Every time a pixel in the mask is black, the corresponding pixel in the layer is transparent. In contrast, as long as one pixel in the mask is white, the corresponding pixel is set to opaque (or solid).
Clipping masks, on the other hand, work more on an inheritance model. All layers affected by the clipping mask actually inherit the transparency values of the clipping layer from themselves.
This means that a completely white layer and a completely black layer would have the same effect as if they were used as clipping masks.
So let’s assume that we want our ink splatter and our woman to be 75% transparent. With a layer mask, we could do this using a lighter gray color.
To achieve this with our clipping mask, we can simply adjust the transparency of our shape. If we take it up to 75%, our masked image automatically inherits the same properties.