With Shape Masks, the creative possibilities are infinite. Basically, you can quickly create a mask in any shape, from an ellipse to a rectangle, to enhance your favorite shots. Instead of removing the cookie from the dough (like in a Shape Crop ), you’re leaving an artistic imprint by adding shapes to your photos. Creating and using masks is a simple way to upgrade your pictures, and Shape Masks offer a straightforward way to add shapes to photos. Shape Masks are one of the best ways to overlay shapes onto your images. How to Use Shape Masks to Boost Your Social Media.