Journal of the Society of Motion Picture and Television Engineers (1950-1954)

dependence will, in turn, be affected by the relative size and importance of shadow and highlight areas. It is probably true, also, that most observers will not be equally critical of the tone-reproduction quality in every area of a positive reproduction. Unless the observers are exceedingly conscientious and painstaking, their attention will be directed critically only to the areas which constitute the center of interest in the scene, or, for more sophisticated observers, to those areas which they feel represent the best clues to tone-reproduction quality. Moreover, because of the limitations of the photographic process, a given exposure will not, in general, produce the optimum quality in all areas of the reproduction. This is particularly true if the latitude of the photographic material is short and the range of luminances of objects in the scene is long. If a color reproduction is being studied, these considerations must be further extended to include the variation in hue and saturation of differently colored objects as the exposure is changed. It is apparent that the use of a limited number of scenes, or of a single scene which is purported to be average, may result in serious systematic errors in determining the average relationship between the overall tone-reproduction quality of reproductions and the camera exposure for a given material. The scenes which were used are illustrated in Figs. 3 through 8. The scene areas included in these illustrations are different in some cases from those in the motion-picture prints, and the tone-reproduction quality of the reproductions is, of course, not representative of that of the projected motionpicture prints. Twelve of the sixteen outdoor scenes included people at various distances from the camera. The subjects of three of the other scenes might be classed as architectural, and the fourth was a landscape. All outdoor scenes were photographed on cloudless or nearly cloudless days to insure that the lighting would remain as nearly constant as possible during the time required for making the photographs, reading exposure meters, and making photometric measurements. All the eight indoor scenes included at least one person. For reasons previously given, none of these scenes is regarded as "average," but, taken as a group, they include characteristics which are found in many of the indoor scenes photographed in Hollywood. Scene 20 is the same as Scene 23, but it was reconstructed and lighted with normal lighting several weeks after Scene 23 had been photographed in low key with strong backlighting. A vivid illustration of the effect of lighting variables on the apparent quality characteristics of the two films is provided by this pair of scenes. Light Measurements Five different exposure-meter readings were made for each scene, as follows: (1) An incident-light measurement was made with the meter at the subject position pointed at the camera. (2) An incident-light measurement was made with the meter at the subject position pointed toward the sun, in the case of the outdoor scenes, and, for the indoor scenes, pointed in such a direction that the highest reading was obtained. (3) A measurement was made of the light reflected from a gray card held in front of the subject's face, perpendicular to the subject-camera axis. (4) A meter with hemisphere was read at the subject position, with the top of the hemisphere toward the camera. (5) A reflected-light reading was made at the camera position. Luminance measurements were made on several areas in each scene, using a Macbeth Illuminometer modified to read the luminance of a field subtending an angle of about 10 min. Photographs 26 January 1954 Journal of the SMPTE Vol.62