We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
16 History of Three-Color Photography
complementary requirement of colorless color-top mixtures there is added the condition that it shall be spectrally complementary. To a given red pigment, which only absorbs the green spectral region, only that green would be complementary, which absorbed all spectrum rays with the exception of this green. Such pigments could be designated "spectroscopic complementaries." Then the absorption band of the printing ink would correspond to the transmission of the filter. Such complementaries can only be determined by the aid of the spectroscope, and this was what Hazura and Hruza tried to do ; but this determination is encumbered with unsurmountable difficulties. If it were possible to sensitize plates for particular regions alone, then it would be possible to use them without filters. The axiom that the filter must be spectroscopically complementary to the printing ink agrees with Vogel's principle : printing and sensitizing colors must be spectroscopically the same, but as practically the former is not permissible, Vogel, although both requirements are correct, advanced the easier proposition.
Howard Farmer's Work. — Farmer28 practically supported von Hiibl's view and, after determining the composition of Maxwell's filters and comparing the results obtained with Ives' and other commercial filters both spectroscopically and in the camera, came to the conclusion that the Maxwell curves "as a matter of fact, do not touch the subject, as they can not be usefully dealt with in practice — they have exclusive reference to the use, for synthesis, of three narrow bands of spectrum rays, for the purpose of a scientific verification of the theory of compound colors, and have no known application to tri-color photography." In a later paper29 the subject was still further elaborated by Farmer, with curves and spectrograms, which prove that the adoption of the Maxwell, or similar curves, as a basis for the production of three-color prints gives a fatal degradation of the colors with black.
Bull and Jolley. — A. J. Bull and C. A. Jolley™ also dealt with this subject and pointed out that too little attention had been paid to the overlapping of the transmissions of the filters, and that the curve of photographic action never corresponded with the visual effect, so that the range of gradation, which even the best plate will record, is less than the eye can perceive; one effect being that the curve of photographic action was steeper than the visual where the filters absorb ; and the dyes used, having abrupt absorptions, any shading off of the limits of the filter records was impossible.
They postulated two fundamental points : first, that since in any photographic process one prints from the parts of the negative where the light has not acted, or there in proportion where the light has not acted, each printing color should consist of white light, minus the colors recorded through the filter. Second : — that the regions where the photographic records overlap should accord in hue with the printing colors of