Journal of the Society of Motion Picture Engineers (1930-1949)

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the Fig. 1 which the authors show represents the familiar sharp drop in television resolution towards the extinction point. However, it has been shown in the work by Schade that if the influence of terminal equipment is considered in addition to that of the electrical circuit, the shape of the characteristic obtained shows a gradual drop, not too different from the photographic characteristic. This is illustrated, for example, by Figs. 100 and 101 of the 1948 paper.6 (e) The authors attribute to Kemp a suggestion for the use of a factor C = 0.75 to compensate for the decay, towards the extinction point, of the resolution of the photographic as compared with the television system. I have read through the Kemp paper referred to, No. 1351, fairly carefully but cannot find the suggestion. (f) The authors mention a proposed signal-to-noise ratio requirement, to avoid degrading the film picture, of 30 db. American estimates of the performance of film run appreciably higher.7 Figures (excluding allowances for synchronizing pulse and excluding frequency weighting) have been presented of 42 to 47 db, and even higher. Possibly the authors are measuring the random noise peak-to-peak, instead of rms, but even this would not account for all the apparent discrepancy. It is noted that no figures at all are given on specifications for shading or phase distortion, although these are apt to be important impairments in presentday television. (g) It would be interesting to know if the authors have any specific information in mind on the "probably greater incidence of vertical than horizontal lines in a natural scene." It is a little odd to find, after an admirable discussion of the advantages to be gained by the presentation to the director of exactly the picture which will ultimately be obtained from the film, that the authors are so little bothered by the problem of flicker on the director's monitor. With the use of the sequential scanning and the frame frequencies mentioned, together with a useful picture brightness, one wonders if the flicker will not be sufficient to ruin the director's artistic judgment. It would be interesting to have more information on the speculations regarding the possibilities of long decay phosphors in avoiding this, without unduly blurring the outlines of objects in motion. References 1. O. H. Schade, "Image gradation, graininess and sharpness in television and motion picture systems: Part I — Image structure and transfer characteristics," Jour. SMPTE, 56: 131177 (see p. 137), Feb. 1951. "Part II — The grain structure of motion picture images — an analysis of deviations and fluctuations of the sample number," ibid., 58: 181-222, Mar. 1952. "Electro-optical characteristics of television systems: Introduction," RCA Rev., 9: 5-13, Mar. 1948. "Part I — Characteristics of vision and visual systems," ibid., 13-37, Mar. 1948. "Part II — Electro-optical specifications for television systems," ibid., 245-286, June 1948. "Part III — Electro-optical characteristics of camera systems," ibid., 490530, Sept. 1948. "Part IV — Correlation and evaluation of electro-optical characteristics of imaging systems," ibid., 653-686, Dec. 1948. 2. C. M. Tuttle, "Density measurements of release prints," Jour. SMPE, 26: 548553, May 1936. 3. "Symposium on Screen Viewing Factors," held May 2, 1951, at the Society's Convention at New York and published in Jour. SMPTE, 57: 185-246, Sept. 1951. 4. S. K. Guth, "Surround brightness: key factor in viewing projected pictures," Jour. SMPTE, 57: 214-224, Sept. 1951. 5. H. J. Schlafly, "Some comparative factors of picture resolution in television Collins and Macnamara: Electronic Camera 459