The art of sound pictures (1930)

COLOR 251 which could be recorded accurately on a full frame of picture film, are lost in the reduction of the picture to onethird the size. As far as now appears, the complicated details of the process, and the subsequent commercial difficulties, are practically as great with this process as with the threefilm process, though improvements are now being made which may eliminate some of the practical difficulties in projection. In describing all the additive processes mentioned above, we have taken them at their best. That is to say, we have described all these processes as using three differently colored filters which alone are capable of giving a perfect reproduction of natural colors. But during the practical use of the Kinema Color process, and at various other times in the development of the additive processes, only two colors have been used. When three differently colored lights are selected, all the spectral colors can be obtained by mixing them in different proportions, as above explained. But if only two slightly different colors are selected, a great majority of the 230 colors can still be obtained by mixing the two basic colors. The usual method of selecting two colors is to divide the entire spectrum roughly in two. As a result, there appears what is usually called the light half of the spectrum and the dark half of the spectrum. The light half begins with red and ends close to the green. The dark half begins with the green and ends in the violet tints which lie beyond the blue itself. Two colors close to the beginning of each half of the spectrum are selected for a two-color mixing process. A bright red or an orange-red may be selected to represent the bright half of the spec