> LAYER MASKS
Modify selections to perfection
Once you’ve converted a selection into a layer mask, a black–and–white thumbnail appears next to the layer in the Layers panel. White pixels make the corresponding layer’s pixels look solid. Black areas create transparent pixels on the image layer. You can apply white brush strokes to the mask to restore missing bits of your subject. Black strokes will hide unwanted parts of the image layer. Layer masks are non–destructive so you can show or hide specific layer content at any time by applying a few more white or black brush strokes.