| 摘要 |
PURPOSE:To facilitate correction processing by extracting a black component from picture signal of respective primary colors, processing it for tone correction of the picture signal, and using the processed picture signal of the black component as a blackboard signal. CONSTITUTION:Input picture signal SR, SG, and SB of respective primary colors R, G, and B are corrected by gamma correcting circuits 11-13 so that gamma=1, and then sent to color changing circuits 21-23, where they are converted into picture signals SC, SM, and SY of cyan C, magenta M, and yellow Y, respectively. Those color-converted picture signals SC, SM, and SY are sent to a blackboard synthesizing circuit 3, which detects a minimum level among signal levels ec, em, and ey of primary colors invariably and uses the detected signal level as a black component. The black component signal SK is sent to a toner correcting circuit 4, which performs nonlinear tone corrections to generates an output signal (blackboard signal) S'K of black. |
