| 摘要 |
PURPOSE:To enable the copying of an original with resulting high definition to be performed, by applying the output of a fixed threshold value register for a block in a diagram area as a threshold value compared with a multilevel picture element, and that of a dither matrix for the block in a photographing area. CONSTITUTION:When a multilevel image signal read in from a scanner 1 is processed, a multilevel buffer memory 2 is divided into block units of (nXn), and the light-and- shade distribution of a picture element in the block is calculated, and a peak value(it is assumed as PL) existing between the lower limit value of a light-and-shade level and a certain threshold value level ZL (the light-and-shade level of the raw material of paper), and the peak value(assumed as PH) existing between the upper limit value of the light-and-shade level and a certain threshold value level ZH, are found, and binarization by the fixed threshold value or an area gradation processing by a dither method is applied on the picture element in the block. In other words, when either the PH or the PL is larger than the threshold value hH, or both the PH and the PL are larger than an hL(<=hH), the binarization processing is applied, and when it is a case other than the above, the area gradation processing is applied. In such a way, it is possible to obtain a copied image with high definition. |
