The history of three-color photography (1925)

606 History of Three-Color Photography carrying the line screen and a third the filter. The line screen frame would come into position at the film change and move intermittently, while the filter frame, in a two-color scheme, would move one-half revolution for each picture and might move continuously. In projection the ordinary shutter was used. Fig. 169 1 represents a perspective view of one form of shutter, filter and screen arrangement; A is a rotary frame carrying the cut-off shutter B ; C is a rotary filter frame carrying the filters D and E and the former was provided with a clear space F for each filter. The spaces G between the sections D and E and the clear section F constitute shutters, which permit the line screen to be shifted out of the optical path. The screen is represented in 2 by a slide H worked by /; J , K is the film which runs over the usual spools L, L; M is the lens. To reduce the action of the violet rays the clear portions might be colored yellow. In 3 the lines are circular to avoid blurring. In 4, 5, 6 other modifications are shown. Screens with 200 to 400 lines to the inch were suggested, but others might be used. The same inventor210 also proposed a screen unit process for doublecoated film, which was exposed on both sides through a screen, but the lines exposed on the one side registered with the unexposed on the other, as shown greatly enlarged in 1, Fig. 170. And 2 is a similar view, I being the celluloid and the small figures the exposed parts. The object is shown diagrammatically in 5, consisting of two white sectors W , W , a red sector R and a green sector G. In 4 section C, the sectors are additively obtained in white by alternating bands of pure red-orange, 5 in 2, and pure green-blue 8 in 2. The section R in C consists of the print on the back of the green-blue negative colored red. modified by the green colored lines 8 on the front, which still additively gives the red print, even although the green lines overlap the red print, narrow bands of black occur. The green sector G was likewise reproduced by narrow bands of green alternating with black. J. E. Thornton211 after summarizing some of the known motion picture color systems, proposed to make a screen negative and claimed that it was possible to expose at the rate of sixteen pictures a second. Any pattern elements could be used, and from this negative the individual records wrere to be prepared. The patterns being obliterated as was done in Dorten's patent and screen-plate work generally. This was to be done by using black and white screens, like Brasseur and others, or by angling the light as in the Powrie, Smith and other methods. F. Habere212 would get over the graininess by enlarging the horizontal elements. S. Kolowrat and A. Nekut213 pointed out that the grain of existing screen-plates w7as too coarse for cine work and proposed to centrifugally separate silver iodide from an emulsion, stain up in the three colors and re-emulsify in gelatin. The dyes were to be fixed with tannin and the silver salt dissolved. As it would not be possible to coat these grains