Method for determining a graphic area ratio of a printing plate and an

Abstract

A computer type setting device (CTI) performs layout of letters and graphic information of a manuscript on printing plates, based on the data transmitted from a keyboard. During such an operation, plate layout data LD such as the font, size, word spacing and line spacing, are determined. Raster image processor (RIP) converts this plate data PD into digitized bitmaps/characters BD, and inputs the results into a layout scanner. The layout scanner converts the digitized pictorial and figure data into 8-bit contrast image data IM, per page of the manuscript, and determines the layout of the images and the contrast data on the printing plates. The dot generator 13 scans the finished plates data PD in a given direction, digitizes the images in terms of [0]s and [1]s into film exposure data ED, and supplies the results to an output scanner and a memory device. The output scanner optically produces positive film nettings, based on the successive film exposure data ED. The exposure data ED is read out at certain intervals by a control device, and is supplied to a plate area ratio accumulating device 16, which computes area ratios SD, according to input from an external source FLD and according to the ink key spacing of the press, to provide a signal to efficiently and effectively control the amount of ink to be supplied to the printing plates so as to permit a high quality printing operation.