Digital processing of document scan - uses nonlinearly encoded digital signal to give image-improving weighting

摘要

Electronic picture or negative scanning and recording equipment uses an opto-electronic scanner and digital processing of the signal. The positive or negative original is illuminated and scanned to produce a signal for the a-d conversion stage comprising a signal shaper and a-d converter. The signal shaping enables fewer equal quantum step analysis to be carried out in later stages instead of using more nonlinear encoding stages. The signal processing stage comprises a store, digital equaliser and the evaluation processing stage. D-A conversion precedes amplification and then a laser light source is modulated to record the image. The quantum steps are divided into a number of stages between a min. and max. density so that the signal shaping and equal step encoding provides a combined non-linear, subjectively-designed result according to the given mathematical expressions.