Using the video lookup table for reflectivity calculations: Specific techniques and graphic results

Abstract Sloan and Brown [ Computer Graphics and Image Processing 10 , 1977, 297–317] have shown that the video lookup table can be used to provide fast and flexible changes to a raster graphic display without changing the image memory contents. By storing encoded surface normal vectors and using the video lookup table to perform reflectivity calculations, the surface may be rapidly displayed under a wide range of lighting and reflectivity conditions. However, there are certain drawbacks. Quantizing the surface normal produces artifacts in the final image unlike those resulting from the usual approach of quantizing the surface brightness. Second, the lighting effects must be independent of object position, and so shadowing cannot be done with this method. Results from the use of this method are shown in photographs of the display of several objects under different lighting and reflectivity conditions, and surface normal quantization schemes.