Photoshop masks for illustration- Part one: Quickmask

If you’ve done much colouring in Photoshop, the chances are you will have come across selections and masking at some point—using the lassos and magic wand tools to cut out areas to work on to save you having to worry about colouring outside the lines and so on. In this set of tutorials I’m going to be teaching you the basics of using the next level up from that: quick mask, layer masks and clipping masks. These features are especially useful in photo-editing, but we can use them in illustration for some really handy shortcuts and effects. Rather than running a step by step on a specific final image, I’m going to be showing you around the basic techniques, so that you can use them in your own art however you like.

This lesson is going to introduce you to a tool called the quick mask. It’s kind of the middle ground selections and layer masks, and we can also use it to very quickly create a black-to-transparent lineart, something that can be incredibly useful to have.

While this isn’t too hard, I’m going to assume you have a basic knowledge of Photoshop for this (what a layer is, the painting tools and so on.) You’ll also need an lineart or a clean sketch of some kind to work with.

Meet the Quickmask

The quickmask is a tool that lets you create a mask or selection with much more precision and versatility than the lasso, marquee and wand tools, allowing you to control the mask using Photoshop’s painting tools. It’s easier to explain through using it than describing it, so we’re going to create a quick demo image so you can see how it works.

1) First, create a new document to work with. It doesn’t really matter what size, but I’ve used a 400×400 square.

Create a new image to work with.

2) Once you’ve got your canvas, grab the lasso tool (by clicking its icon in the tool bar or by hitting the L key) and draw yourself a random shape.

Mask off a shape with the lasso tool

3) Now to check out our mask. The quickmask button can be found under your foreground and background colours on the tool bar: it’s the little rectangle with a circle inside it:

The Quickmask Button

You can also access it by hitting the q key.

When in quickmask mode, you’ll be able to see your mask or selection as a transparent red film covering the areas that are not selected.

A Basic Mask

Now here is where it gets interesting. The mask is effectively a greyscale image, with the white areas being fully selected, and the red fully deselected. But it isn’t just on or off: shades in-between will be partially selected. And it’s not just there to look at—we can edit it too.

4) You can edit the mask with pretty much any painting tool Photoshop has. Grab some brushes with different hardnesses and textures and throw down some scribbles to test this out.

Painting into our mask

Use white for areas you want to be selected, and black for parts you want to mask away. You can also use blending modes like screen or multiply on your brushes if you like, just like working into any normal greyscale image.

5) Hit the quickmask button again (or press q) to get back to normal mode. You should see the ‘marching ants’ dashed lines around the rough areas of your mask. Don’t worry if it seems like your detail has been lost, it hasn’t.

Back in normal mode

Hit ⌘+h (ctrl+h on windows) to hide the marching ants. (You can bring them back by pressing it again.)

6) Now to actually use that mask for something. In this example, I’ve just thrown down a simple gradient.

Applying a gradient using the mask

You can use your mask to apply anything—painting, fills, even image adjustments and filters.

7) You don’t just have to use the brush tools to edit the mask either. Anything that can work with a greyscale image will work, including gradients, pattern fills, filters and even cut and paste.

Using a round gradient as a mask

Painting with a round gradient mask

The applications for masks are endless, from just using them to avoid painting in certain areas, to more complex uses like selectively blurring different parts of your image to different levels. The ability to use cut and paste inside quickmask mode also gives us a quick way to create a mask from a lineart, which we will be looking at in the next part of this lesson.