| 摘要 |
857,234. Copying by scanning. CROSFIELD Ltd., J. F. July 17, 1959 [July 18, 1958; Nov. 13, 1958], Nos. 23161/58 and 36563/58. Class 40(3). [Also in Group XL(c)] A colour-component printer for use in an image reproduction process is obtained by exposing a photographic plate 14 in direct contact with the corresponding one of three uncorrected colour separation transparencies 12 in an electrooptical scanner in which light from a cathode-ray tube 6 passes through the transparencies to photo-electric cells 16, the three cell signals being applied to a computer 20 to derive a colourcorrection signal, the signal from the cell representing the colour component corresponding to the printer being applied to a non-linear circuit to obtain a tone-correction signal, and the colour- and tone-correction signals being combined at 19 and applied to modulate the intensity of the scanning spot in the cathode-ray tube. Desirable tone corrections to be effected by circuit 18 are described with reference to Fig. 3 (not shown) and a suitable non-linear circuit is described with reference to Fig. 4, (not shown), (see Group XL(c) ). Plate 14 is provided with a backing filter 32 such that it passes light to which the emulsion is insensitive. Diffusing plates 34 are placed behind the other two transparencies. An additional photo-electric cell responsive to light direct from the screen of the cathode-ray tube may be employed in a system, Fig. 2 (not shown), for removing from the signals from photo-electric cells 16 the modulation imparted by the colour- and tone-correction modulation of the scanning spot. In a modification the modulation signal for the cathode-ray tube may be subtracted directly from the photo-electric cell behind photographic plate 14. The signals applied to the cathode-ray tube may be chopped so that the photo-electric cells produce alternating signals. A rotating drum or oscillating table scanner may be used in place of a cathode-ray tube scanner.
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