What is masking?
Masking allows us to determine which part of a layer is shown or hidden in our document by restricting its visibility. In practical terms, this means:
We can apply adjustment and filter layers selectively to certain areas of an image—anything from tonal adjustments to blurs, sharpening filters and distortions.
We can composite parts of separate images into one main composition, giving us creative freedom to create entirely new images.
Because of masking, we can do the above non-destructively by adding what are called Mask Layers to our document. Consider this compositing example:
Here we can see we’ve pasted two entirely separate images on top of our base image. Let’s say we wanted to cut out the stones from these two pictures in order to place them into the foreground of the base image.
Typically, we would use selection tools to isolate the stones and delete the rest of the images—physically removing those pixels. Rather than deleting or erasing, however, we could instead mask the unwanted areas out, meaning they would simply be hidden from view.
Masking the unwanted areas would be a non-destructive approach—the benefit being that we could go back and change, revise or tidy up the mask at any point during editing, including using selection refinement if the mask’s edges are rough or inaccurate. Had we erased the unwanted pixels, we couldn’t do this.
Masking is also a popular way to restrict filters and adjustments to specific areas. In this image, for example, we might want to desaturate the background colours whilst keeping the vibrant reds. Additionally, we may also choose to add some diffuse glow, but only to the text.
Using masking for both these cases allows us to achieve the look we’re after, rather than desaturating the entire image or having a distracting glow over the background areas as well.
Painting and Gradients
Masking can be defined not just from selections, but also from colour and gradient fills. Here, for example, we might wish to restrict tonal adjustments to the sky of the image by adding a gradient fill as a mask, which provides a smooth transition for the adjustments.
Masking and Affinity Photo
Affinity Photo has comprehensive masking support, and masks can be created through selections, colours, fills and channels.
A unique feature of Photo is that Adjustments and Live Filter layers inherently have their own layer mask, and can instantly be masked without having to add a nested Layer Mask to them, saving time and making for a more efficient workflow.
Masking and Affinity Designer
Although masking is used less frequently in Affinity Designer when compared with Affinity Photo, its vector masking features do come in handy.
In Designer, you can use the Pixel Persona’s Erase Brush Tool on a vector shape to remove unwanted areas. A Mask Layer will be created automatically when you erase on the vector layer, allowing you to edit non-destructively.
Alternatively, you can use Pixel Persona’s Paint Brush Tool to paint with a black brush to erase, and even restore removed areas by swapping to, and painting with, a white brush.
Masking and Affinity Publisher
From Affinity Publisher, you can use StudioLink to quickly switch between each of the Affinity apps’ features, using the Photo Persona’s masking capabilities to mask areas of an image placed on a page from within the same app.
Publisher’s own masking capabilities allow you to create some unique and interesting effects, for example, creating a mask to display an image within a headline.