The art of sound pictures (1930)

252 THE ART OF SOUND PICTURES trum, and a green or blue may be selected to represent the dark half of the spectrum. When only two colors are used in this way, certain natural colors can never be photographed or reproduced. Yellow, for instance, cannot be recorded, nor can purple or blue itself, if red and green are the basic colors selected. If blue is chosen instead of green, then a true green cannot be obtained, and there is still difficulty in getting yellow, violet, lavender, etc. If orange-red is selected instead of red, a bright red can never be obtained from the mixture. Use of two colors in a process such as Kinema Color of course has distinct commercial advantages. Only two separate pictures of each object or movement need be taken, instead of three. This reduces both the speed at which the film must be run while taking the picture and also the required speed of the film during projection. It is sometimes asserted, also, that, with the two-color process of the additive t}q)e, there is less fringe flicker and pulsation. But, for various psychological reasons, this statement is somewhat questionable. It can be said, at least, that there is very little difference, in these unpleasant effects, between the two-color and the three-color process, provided the film is run through the projection machine at adequate speed for each process. SUBTRACTIVE PROCESSES Both the commercial processes now in use in Hollywood are subtractive processes. Both are two-color processes only. They are called Technicolor and Multicolor. In describing the general principles of subtractive processes, it will probably be most practical to use the Techni