Layer Masks Made Easy
In this tutorial we will use very simple graphics to understand layer masks. Layer masks scare a lot of people, but they are actually really simple. If you’ve done the original seamless background tutorial you should now understand what a layer is. Each Layer is a separate image that is combined with our other layers/images to create a final project.
A layer mask is simply a way to hide and show different parts of your layer. You can add a layer mask on any layer by right clicking on that layer in the Layers dialog and then clicking on Add Layer Mask. By default the color white is fully opaque and black is fully transparent. That means any part of the layer mask that is completely white will make that part of the parent layer fully visible. Any fully black portions are fully see through on the parent layer. Using black to white gradients on a layer mask makes a soft transition from transparent to opaque.
Enough talk, lets make a project and see layer masks ourselves.
Let’s make a new image 256 x 256 any color of your choice. Add a 2nd layer and fill it with any other color that you’d like. We’re using ctrl-a (select->all) then the paint bucket tool to fill the layer. As you see we have a very simple image so far.
Now we will add our layer mask. Right click on the upper layer in the layer dialog box shown, in my case here it’s the blue one. After right clicking, click Add Layer Mask from the menu that appears. Leave the default setting of White (full opacity).
Hit okay and we will now see our white layer mask in the layer dialog box right next to the image, again in my case the blue layer. You can now click on the small swatches in the layer dialog to choose either the image layer or the layer mask to edit. The currently selected object will have a white border around it. Click back and forth a few times until you are comfortable.
Now let’s focus on our image dialog for a minute. Use the rectangular selection tool and select a box in the center of our image. This will be our layer mask. Make sure to select pure black as your foreground color.
Now use the paintbucket tool to fill our selection with black. But we won’t see black unless that is the color of our bottom layer. If you have selected the layer mask, you’ll see the black square in the layers dialog box.
That is what layer masks do. Anywhere there is black in our layer mask we can see through our layer to the layer below. They are simple to use, but can be used to great effect in your graphics.
One last thing we’ll look at in this tutorial is the use of gradients in the layer mask. This allows you to blend the images together and achieve better results in many situations. So, let’s set our foreground color to black and the background color to white. We want to effect the entire image, to hit ctrl-a (select->all).
Now click on the gradient tool on our toolbar. Let’s leave the default options that appear in the graphic below. It will be a linear gradient from the foreground color (black) to the background color (white).
Now click in the upper left corner of the image dialog and drag down to the bottom right. The gradient you select will always follow the path you set for it by clicking and dragging. You can use any of the gradient styles for the layer mask, but it must always be black to white or vice versa.
I hope this tutorial has helped you to grasp the fundamentals of layer masks. While we didn’t really do anything exciting here, we put down a solid foundation on a feature that is used to accomplish a lot of things with images. They can be used to blend images, make a logo stand out and other interesting effects.
Layer masks are essential if you hope to work in some portions of the graphics industry. They are also known as the opacity channel and are required in certain professional projects, especially if you work in television.