| 摘要 |
PROBLEM TO BE SOLVED: To perform optimum conversion according to a color image to be converted by analyzing a color-value frequency distribution of pixels by color components and detecting a color value area, expanding the color value area and generating a conversion table consisting of color values before and after expansion, and converting a color image into a monochromatic image. SOLUTION: Multi-valued color image data of R, G, and B held in an auxiliary storage device 4 are read in a RAM 2, only R components of the color image data are extracted, and a histogram of the number of pixels to color values is generated and recorded in the RAM 2. The histogram is so shifted so that only an area having the number of pixels larger than a threshold value previously set for the histogram is regarded as an object. A new color value area is regarded as an object area of color/black-and-white conversion thereafter to obtain proper contrast to be converted. With the new histogram, a color value area having no distribution of pixels is detected and stored. Further, a conversion table having the same color value after conversion with input color values is generated and the R value process is completed. |
