When you’re working in a full color document in Adobe InDesign, you may occasionally want to see how the image looks in grayscale rather than full color. Normally this would require you to convert the image to grayscale in your favorite image editor. But you can quickly get an idea of how it will look without even leaving InDesign. Here’s how you do it:
Simply draw a box on top of your image and fill it with black, then in the Effects panel, set the Blending Mode in the drop-down menu to Saturation. This will give your image a sudo-grayscale appearance. It’s not perfect, but it’s a quick enough method to preview what it will look like (see the image above, original image on the left, adjusted image on the right).
For some extra fun, you can fill the box with a color and change the Blending Mode to get some neat effects.
In the image above, I filled the box with a bright orange color. The box on the left has the Blending Mode set to Saturation, the box on the right is set to the Hue Blending Mode.