| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent lowering of the number of gradations or substantial contrast and to correct variation of a light quantity of an output to be in an extent having no problem by a method wherein a light quantity level of the light output from an optical output medium is made non-uniform in a specific gradation region when the variation of the optical output from the optical output medium is corrected. SOLUTION: A PLZT print head 20 can execute optical writing of a color image and uses a regular halogen lamp 21 by switching three colors of red, blue and green by virtue of rotation of a color filter 22 corresponding to a required time. After a light passing through the color filter 22 passes a thermal absorption filter 23, it passes through a glass rod 24 and a high speed rotational disk 25 to be a uniform distributed light which is guided to an optical shutter through a light guide 26. A specific gradation region corresponds to a region in a photographic paper 4 to be optically written wherein variation of the output density with respect to variation of input light is sufficiently and visually small. As a result, the output density is not varied very much and the variation is not visually observed even when the correction is not uniformly executed and noise is remained.</p> |
