| 摘要 |
PURPOSE:To improve the quality of a color reproducing picture and to simplify the circuit constitution by discriminating that an achromatic color component of a color picture signal is in high resolution area or contrast area and changing the threshold value of binary-coding of the color component signal depending on the result of discrimination. CONSTITUTION:An input signal is A/D-converted by a three-color separation original reader 301 in a color picture forming device, B, G, R component signals are outputted, they are converted for complementary color at a circuit 302, corrected for gradation at a circuit 303, a background color eliminating circuit 304 separates a black component K (achromatic color component) and a chromatic color component, they are corrected by a masking circuit 305 so as to attain binary-coding as to color components Y4, M4 and C4. A discriminating circuit 307 discriminates whether a data in a picture element block of the black component is in a high resolution area or a contrast area, and when the data is in the high resolution area, its output activates threshold value changeover switches 308 and 316 so as to change over the threshold value source to prescribed threshold values 309 and 314, binary-coding circuits 306, 311-313 convert the data into a binary-coding data depending on the threshold values and when the data is in the contrast area, a threshold value signal is supplied from dither memories 310, 315.
|
