| 摘要 |
PURPOSE:To enhance the contrast of an image and contrive to enhance image quality, by a method wherein the diameter of dots formed by a printing head for black is set to be larger than the diameter of dots formed by other printing heads. CONSTITUTION:Input R, G and B signals are processed by a YMC converting circuit 1, a gamma-correcting circuit 2 and a masking circuit 3, and the processed signals are inputted into an under color removing circuit 4 and a signal selector 6. A comparator 5 compares a preset threshold value Vth with a BK signal from the circuit 4, while the signal selector 6 selects either one of a signal from the masking circuit 3 and a signal from the circuit 4, and outputs the selected signal as an output signal. In this case, since an analog printing system is used, large dots are printed with higher density while small dots are printed with lower density, for each picture element. Accordingly, when the diameter of the dots formed by the printing head for the BK signal is set to be larger than the diameter of the dots formed by other printing heads for other three color signals so as to print the black dots with higher density, it is possible to enhance the contrast and the image quality. |
