PICTURE SIGNAL PROCESSING UNIT

摘要

PURPOSE:To improve the quality of a line drawing and a character picture by discriminating whether an area is at a low frequency area or a high frequency area depending on the density difference from that of surrounding picture elements and applying optimum interpolation in response to each area. CONSTITUTION:A differential arithmetic means 209 of an area discriminating means 214 calculates a difference between a density level of a noted picture element and a mean density level of a surrounding picture element area. Then the difference is compared with a prescribed value by a comparator means 211 to discriminate whether the area is at a high frequency area or a low frequency area. A selector 207 is switched by the discrimination signal to select the repetitive interpolation of the density level of a noted picture element in case of high frequency area and the interpolation of the average calculation is selected in case of a low frequency area and an output is given at an output terminal 208.