Learn how to make amazing fantasy landscapes quickly!
Pick the most suitable method for creating your mask. For example, here circular planets are cut out using the Elliptical Marquee tool. Use the Pen tool to cut out more complex objects, for example, to isolate the rock tops.
When everything is cut out, bring the new elements onto your canvas. Use your masks to integrate them into your scene by keeping some foreground elements in front. Use tools such as Feather and Refine Edge to edit masks.
Once the masks are perfect on each object, you can add adjustment layers. Use masks here to keep adjustments specific to certain areas of the composition. Using the Gradient tool with masks can create a smooth effect transition.