| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the need of a delay memory for obtaining a γ value and to reduce a cost by changing the density of dots to multi-valued images and controlling the density γ. SOLUTION: Image signals from an image read part 1 are made multi-valued in a multi-valuing circuit 2 and stored in an image memory 3. A γ conversion circuit 5 turns the image of N1 bits to the number of gradations converted image of N2 bits by a first gradation conversion processing, then performs a γ conversion processing by prescribed coefficients (a) and (b) set corresponding to the number of bits in EE and γ setting circuit and obtains a density value. In this case, depending on the values of (a) and (b), in the case that the density value exceeds the range of the N2 bits, clipping is performed by the number of bits larger than N2. A second number of gradations conversion processing is performed to the density value by an error diffusion processing, and at the time, by appropriately selecting the number of output bit corresponding to the image, noise is reduced and the degradation of image quality is suppressed by a clipping processing. Thus, the need of providing a memory used only for an EE processing is eliminated. |
