Method and apparatus for producing binary picture with detection and retention of plural binary picture blocks having a thin line pattern including an oblique line

摘要

Binary picture reducing method and apparatus are disclosed, wherein an original picture is divided for a block of a pattern matrix composed of a predetermined number of picture elements, thereby extracting a plurality of binary picture blocks. When the plurality of binary picture blocks each agree with a predetermined thin line pattern, the binary picture block is detected as a thin line block. The thin line block thus detected is retained on an output picture at a position corresponding to a predetermined reduction ratio.