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.
30 History of Three-Color Photography
the fault where it actually lies — in the inks — and not strive after an impossible separation of colors.
Much perplexity has been caused by the shibboleth of the "impurity" of the inks. It is said that correct reproduction of colors is not possible because the inks, in comparison to the spectral colors are "impure." The dinginess of our inks can only have the effect of making compound colors appear dingier than in the original, but on the correctness, that is on the the tone of the color it has no effect. The fact that the colors reflect other rays of the spectrum has also no bearing on the possibility of three-color printing. Colored glass also lets through many rays yet it acts exactly as though it passed naught but pure spectral rays.
The so-called impurity of the colors has nothing to do with the incorrect reproductions in three-color printing, but it has been found a plausible ground for the incompleteness of the process from a want of complete theoretical knowledge.
To match the theoretical colors von Hiibl recommended erythrosin, filter yellow and patent blue in the strengths 0.5, 1.0 and 2.0 per square meter.44
E. Sanger-Shepherd45 defined the printing colors as pink or magenta, such as is obtained by admixture of the fundamental red and blue-violet; a pure yellow formed by the admixture of the fundamental green and red, and a bluish-green formed from the fundamental green with the blue-violet. Pink, crimson or magenta are synonymous.
Abney46 dealt with the subject of printing with transparent inks or colors, and though there is no doubt that he had in mind transparencies produced by superposed films, a brief note as to his conclusions may be worth recording. His whole argument is based on the color sensation curves, as determined by him, and he said : "arguing then from this we find that the inks to be used for printing in transparent colors should be such that their principal intensity, when superposed in pairs, should be near the colors which should be used for the triple projection process, and should end not far from this point in the spectrum. The overlap of the absorptions should be as far as possible, as is consistent with sufficient intensity, if great purity is required. In choosing colors a great point to aim at is that they should, when of full intensity, match the spectrum color (or mixture in the case of purple or pink) with only the smallest addition of white light to this latter. This will indicate that they do not transmit so much of the spectrum as to be harmful. If the intensity of the spectrum colors, when the spectrum is of a certain brightness, matches that of the inks, it may be taken as indicating that the latter are of proper intensity, and finally these intensities of ink when superposed should give a black. If the black is of reddish or greenish cast, it shows that the colors have not been rightly chosen."
A. J. Newton47 examined the colors used for producing carbon prints,