Raking light is a technique in which a painting is illuminated from one side only, at an oblique angle in relation to its surface.
Raking light is used to reveal a painting’s surface texture. Raised paint surfaces facing the light are illuminated, while those facing away create shadows.
The increased appearance of paint texture can easily be seen, photographed or recorded digitally. Conservators use raking light to judge aspects of the condition of a painting.