Brightness Engineering

(I) Introduction Brightness engineering may be regarded .as illuminating engineering extended to include the planning of brightnesses and brightness ratios. It is a new development in so fa r as it is an attempt to plan not only the illumination on a plane of reference but the brightness distribution of the entire field of view. If the premises on which it is based are sound, brightness engineering represents design for vision in its widest sense. I t does not, however, represent a breakaway from existing illuminating engineering practice but rather a rationalising process. 'The methods of glare control a t present used and the illumination of surroundings, combined with correct colour treatment, are brightness engineering applied by rule of thumb and the guidance of experience. There are three conditions which must be met before brightness engineering can be accepted as practicable : ( 1 ) There must be agreement regarding desirable brightness ratios, i.e., some form