GB1038013A - Improvements in or relating to colour television cameras - Google Patents

Abstract

1,038,013. Colour television. MARCONI CO. Ltd. Nov. 18, 1964 [Jan. 16, 1964; July 22, 1964], Nos. 1915/64 and 29567/64. Heading H4F. In a colour television camera relatively narrow-band signals corresponding to lowdefinition colour and luminance information are produced by a plurality of different colour pick-up tubes each corresponding to a different primary colour image and these signals are supplemented with wide-band high-definition signals complementary thereto derived from a luminance pick-up tube. Fig. 1, of the drawing accompanying Provisional Specification (not shown), depicts one arrangement in which signals derived from pick-up tubes for the primary colours R (red), G (green) and B (blue), and which tubes may be of comparatively poor quality, are fed via respective low-pass filters, to gamma-correcting circuits RGC, GGC and BGC together with signals derived from a highquality luminance pick-up tube Y and fed via a high-pass filter YHP the pass-band of which is complementary to that of the low-pass filters. In a modification of this arrangement the green pick-up tube is not employed, the green signals being derived by a known matrixing technique (Fig. 2, Provisional Specification, not shown). A preferred arrangement is shown in the drawing accompanying Provisional Specification 29567/64, where the outputs of the low-pass filters are combined in a matrix M 1 in the proportions 0À3 RN+0À59 GN+0À11 BN to produce a narrow band low-definition signal YN which is then subtracted from the wide-band luminance signal YW to produce the required complementary signals YD for combination with the low-definition signals at the inputs to the gamma-correcting circuits.