Luminance masks use brightness levels to control what parts of a layer are visible, essentially using light to unveil your design. Bright areas in the mask show more of the layer beneath, while darker areas conceal it. Think of it like a dimmer switch: the brighter the mask, the more you see underneath.

This tool is perfect for creating depth or focus in images, like highlighting a subject in a photo while subtly fading the background. It's also great for UI design, where you might want to draw attention to active elements by making them brighter and more visible.