| 摘要 |
PURPOSE: To obtain image data whose resolution is enhanced with fidelity to a substantial image without causing a pattern such as a stripe pattern. CONSTITUTION: A threshold level generating circuit 10 selects 1st and 2nd level used to divide usually a read range into three equal divisions as threshold levels TH2, TL2. When delay circuits 1-3 and comparator circuits 4-7 are used to discriminate picture element data received by a comparator circuit 8 and three preceding picture element data to have a medium luminance, a 3rd level used to divide a read range equally into two is outputted as threshold levels TH2, TL2. Then the comparator circuit 8 classifies each picture element into three luminance being high luminance over the threshold level TH2, a medium luminance between the threshold levels TH2 and TL2, and a low luminance smaller than the threshold level TL2 based on the threshold levels TH2 and TL2 outputted by the threshold level generating circuit 10, and a resolution conversion circuit 11 converts the picture element with high luminance into two white level picture elements, the picture element with medium luminance into one white level picture element and one black level picture element and the picture element with low luminance into two black level picture elements. |
