Television Images: The Illusion of Space and form Aided by Lighting

Leonordu, Vol. 9, pp. 222-223. Pergamon Press 1976. Printed in Great Britain TELEVISION IMAGES: THE ILLUSION OF SPACE AND FORM AIDED BY LIGHTING Ray E. Knight* 1. This note is based upon my TV lighting and colour selection lectures presented to personnel at Rediffusion Television, Hong Kong, prior to their commencing a full colour TV service in Chinese and English by 1974. Some of the problems in lighting and colour selection are related to those of a painter attempting to represent space and form on a 2-dimensional surface. Although their electronically operated cameras are up-to-date, the floor areas and the lighting facilities in the Hong Kong studios are surpassed significantly by those in the more important studios in Europe and the U.S.A. Thus, there is a problem in conveying an illusion of space in films and videotapes produced in Hong Kong comparable to that obtainable in those imported from abroad. Fig. 1. View of TVpictrrre showing a sphere with side and hackgroimd lighting. (Courtesy of Rediffusion Television, Hong Kong.) 2. The illusion of depth in paintings and TV images may be by perspective and by several other cues that viewers have learnt to recognize [I]. Among those that often give the effect of relative distance (nearer and farther) are: (1) tone (darker and lighter), (2) size (bigger and smaller), (3) vertical position on the picture surface (lower and higher), (4) quality of edges (sharper and more blurred) and (5) overlap (front and behind). In TV there are additional cues, such as motion (faster and slower) and sound (louder and quieter). The relative capacity of each of the above aspects to evoke a response depends upon the pictorial composition. In certain compositions, for example, the quality of edges may be more significant than, say, size. Space is recognized in a TV picture by the known sizes of familiar objects and the sizes of their images as controlled by linear perspective. However, in order to enhance the feeling of space between objects, their tonal differences may be modified appropriately by lighting. An example is given by an announcer’s face and the background. If the face and background were shown in the same tone, they would tend to be seen in the same plane. If the background is made darker than the face (contrary to the use oftone as a cue for distance) and if a chair or some other object in the background is partly obscured by the head (overlap) and is shown somewhat out-of-focus (more blurred), a spatial difference between the head and background is suggested . 3. The form of an object is perceived commonly when * Artist and television engineer living at 59 Shaef Way, TeddingtonTWI I ODQ, England.(Received 17 Aug. 1975). those surfaces of the object in view are disposed at different angles to rays of light from a single light source. The surfaces of a uniformly coloured object facing the light source appear lighter than those tilting away from it. In the case of a curved convex surface, a highlight may be seen. The only visual cue revealing the form of a uniformly coloured sphere is a variation in tone, that is, a nonuniformity in the distribution of light reflected from its surface. Fig. 1 shows such a sphere illuminated from one side. In Fig. 1 there is the additional factor of nonuniformity in tone of the background, which accentuates the contrast at both the right and left. If the sphere’s surface were illuminated uniformly and the background appeared to have a tone different from that of the sphere, it would appear as a 2-dimensional white object, a disc. On the other hand, if the background only were illuminated, the sphere would appear in silhouette, a dark disc. An illuminated box is shown in Fig. 2. One side is directly illuminated and is indicated by a vertical white chalk line on the far right edge and by the chalk line on the left with hatching over the shadow adjoining the lit side. These two vertical white lines show the boundaries between light and dark that contribute to an illusion of depth. The head, as shown in Fig...