. Practical physics. ingredients fromwhite light. The process of three-color printing consists inmixing on a white background, that is, on white paper, thethree primary pigments in the following way: Three differ-ent photographs of a given-colored object are taken, eachthrough a filter of gelatin stained the color of one of theprimary colors. From these photographs halftone blocks are made in the usual way. The colored picture is then madeby carefully superposing prints from these blocks, using witheach an ink whose color is the complement of that of the filter through which the original negat
. Practical physics. ingredients fromwhite light. The process of three-color printing consists inmixing on a white background, that is, on white paper, thethree primary pigments in the following way: Three differ-ent photographs of a given-colored object are taken, eachthrough a filter of gelatin stained the color of one of theprimary colors. From these photographs halftone blocks are made in the usual way. The colored picture is then madeby carefully superposing prints from these blocks, using witheach an ink whose color is the complement of that of the filter through which the original negative was taken. Theplate on the opposite page illustrates fully the process. It willbe interesting to examine differently colored portions with alens of moderate magnifying power. 473. Colors of thin films. The study of complementary colorshas furnished us with the key to the explanation of the fact,observed in § 464, that the upper edge of each colored bandproduced by the water wedge is reddish, while the lower edge. % TiiKEE-CoLOR Printing 1, yellow impression (negative made tlirougli a blue-violet filter); 2, crimson im-pression (negative made through a green filter); 3, crimson on yellow; 4, blueimpression (negative made through a red filter); 5, yellow, crimson, and bluecombined (the iinal product). The circles at the right show the colors of ink usedin making each impression. Notice the different colors in 5, which are made bycombining yellow, crimson, and blue COLOE AI^D WAVE LEI^GTH 409 is bluish. The red on the upper edge is due to the fact thatthere the shorter bhie waves are destroyed by interference anda complementary red color is left; while on the lower edgeof each fringe, where the film is thicker, the longer red wavesinterfere, leaving a complementary blue. In fact, each wavelength of the incident light produces a set of fringes, and it isthe superposition of these different sets which gives the result-ant colored fringes. Where the film is too thick the overlap
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectphysics, bookyear1922
