| 摘要 |
PURPOSE:To express the halftone of gradation image data without destroying document data by deciding a gradation data area and executing dither processing based on the decided result. CONSTITUTION:When the nXn area of image data (a) is decided as the gradation image data by a decision control circuit 3, the current coordinates of the nXn area are registered in a gradation image data area information register file 6. While shifting the nXn area, the number of image density levels in the area is similarly decided. When the gradation data area is decided by prescanning, main scanning is executed in order to read out the succeeding input data. In this case, the gradation data area is dithered by a dither pattern 8 based on the information obtained from main and subscanning direction counters 4, 5 and the file 6. Thus, the halftone of the gradation image data can be expressed without destroying the document data.
|
