Step 1. Open the photo that you want to alter within Photoshop. Step 2. Click on one of the Marquee tools from the Photoshop toolbar. If you want to soften the edges of your photo in a rectangular or square fashion, select the Rectangular Marquee tool.If your image is round or another shape, select the Elliptical Marquee tool.rag your cursor around the image, creating a border around the image where you want the edges to be softened. Step 4. Click Select, from the top menu, and then click Modify, and then click Feather.. This opens a Feather Selection dialog box.