Luminosity Mask provides a custom compositor node setup to create selections based on image brightness within Blender. The nodes generate monochrome masks that isolate highlights, shadows, or mid-tones, functioning identically to brightness-based masks in dedicated image editing software. These masks can be mapped as alpha inputs to other nodes, restricting color or contrast adjustments solely to the targeted luminance range without impacting unwanted areas.

The setup can be used to locally enhance contrast, protect shadows from clipping, or blend multiple exposures. An included example file demonstrates an Orton Effect implementation using the luminosity masks to isolate tonal changes.