James Kajiya's 1986 rendering equation expressed image synthesis as a light-transport balance between emitted and reflected radiance, giving ray tracing, radiosity, and later path-tracing methods a common theoretical framework.
Turner Whitted's 1979–1980 ray-tracing work showed how recursive rays could model mirrors, transparent materials and hard shadows in a unified image-synthesis algorithm.
The 1984 radiosity work of Cindy Goral, Kenneth Torrance, Donald Greenberg and Bennett Battaile brought object-to-object diffuse light exchange into image synthesis and made color bleeding a computed consequence of scene geometry.