One of my favorite (and more useful) ways to use raster images in Illustrator is to apply a mask. A mask is a way to hide part or all of an image—using a solid or transparency (alpha) mask.
Here’s how we create a simple mask for an image:
- With the Selection tool, select the image you want to mask.
In the Control panel, click the Mask button. This creates a vector shape the same size as the raster image and applies it as a mask (see Figure 6).
Figure 6 Creating a simple mask for an image
You can then edit the mask with the Selection tools. If you want to edit the image within the mask, you can click the Edit Contents button on the left side of the Control panel and edit the image (see Figure 7).
Figure 7 Edit a simple mask
Here’s how we create a transparency (alpha) mask:
- Create a vector shape that will become the mask.
- Apply a black/white gradient fill to the shape. You can edit it later.
- Place the gradient-filled shape over the raster image and select both objects.
In the Transparency panel, click Make Mask (see Figure 8).
Figure 8 Make the transparency mask
In order to edit the mask, you click the mask thumbnail in the Transparency panel. You can then select the mask shape on the artboard and make changes. Make sure you select the image thumbnail in the Transparency panel to continue working (see Figure 9).
Figure 9 Reselect the image thumbnail