GB1279296A - Composition system - Google Patents

Abstract

1279296 Cathode-ray tube displays; facsimile signal reception IPC SERVICES Ltd 11 June 1970 [23 June 1969 (2)] 31645/69 and 31646/69 Headings H4P and H4T An arrangement for producing a visual image (e.g. on a CRT, or on a photographic film for production of a printing plate) of typescript or other material from a computer output comprises a converter receiving data from the computer in an asynchronous form and producing suitable bright-up signals for use with a linear raster type scan. As described the computer 1 sends the image data in parallel (24 bits) runlength coding form (i.e. in words designating alternately white and black lengths of line for the line scans) to the converter which stores the words and counts down the lengths while providing a "white" or "black" output to the facsimile receiver 3. The arrangement may also (when, as shown, the unit 3 is a photographic facsimile receiver) comprise an additional receiver 5 to provide a directly visible display, and a facsimile transmitter 7 synchronized with the receiver 3 for superposition of an image therefrom on the data from computer 1. The specification describes arrangements by which the run-length words (see Fig. 3, channel 1) are stored, counted down and demanded from the computer by converter 2, and the optional facility of receiving direct bit-by-bit bright-up instruction words (Fig. 3, channel 2) (about 1000 words per scan line) in addition to the run-length coded words for superposition therewith; thus enabling a variety of captioning, and pattern generating. Two buffer stores are provided in the computer for each of channels 1 and 2, thus enabling one to be filled while data from the other is being transmitted to the converter. An embodiment for colour reproduction in which three facsimile receivers each producing a colour image are operated in succession is shown schematically (Fig. 5, not shown).