RAY is an extension that is specific to files associated with a software tool for creating 3D scenes called Rayshade. RAY is a file used to store images generated on the basis of the Ray Tracing algorithm. Technically speaking, RAY is a plain text file that defines all the elements of an image. Data from such a file is properly interpreted by the Rayshade engine and an image is generated on this basis.

Rayshade is a cross-platform tool, but rarely seen these days. It was developed at Stanford University.