glsl-luma is a small GLSL module that calculates the luma (brightness) of an RGB color, primarily for converting images to greyscale. It's designed for graphics developers working with GLSL shaders who need to determine the perceived brightness of a color. The library provides a simple function that takes a vec3 or vec4 color input and returns the luma as a float, making it easy to integrate into shader code for various visual effects.