| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image forming method by which the density characteristic of tone expression is made linear by performing printing only at such a gradation level that the density characteristic is linear. SOLUTION: By measuring the quantity of reflected light detected by a reflection density detection sensor 19, the density of an image on paper 22 is found through a density conversion table. Next, the highest gray level of a gradation pattern is detected, and a density range is trisected by setting a level at which nothing is printed as the lowest gray level. Then, gradation levels most approximate to the density levels of two boundary tones formed by trisection, for example, two gradation levels such as 8 and 10 are decided. Four levels, that is, two decided gradation levels, the highest gray level and the lowest gray level of the gradation pattern re dacideed as an output gradation level and outputted to an image forming device for four tones. Thus, the output gradation of four tones where the density is nearly linearly changed is obtained and the density expression of the image in printing is performed according to four outputted tones. |
