| 摘要 |
PURPOSE:To obtain a picture close to an original half tone picture by selecting an optimum opening among plural types of openings through the prescribed arithmetic at every picture element, and taking the counted value of self picture elements in the opening for an estimated reduction half tone picture value. CONSTITUTION:According to a threshold matrix the original half tone picture is converted into a black and white binary picture (dither picture). Conditions that there is no change in a picture element level are decided as inequalities show, and the opening to be used is decided. Self picture elements in the opening selected at every picture element are counted, and a value obtained by multiplying said counted value is considered to be the estimated value of the reduced half tone picture. Thus an operation calculating the estimated value is repeated to obtain the estimated reduction half tone picture. When it is binarized with the aid of the dither matrix, the reduced binary picture (reduced dither picture) can be obtained. |
