| 摘要 |
PURPOSE:To execute tonal correction with almost no color blurring by separating lightness signal component from three primary color signals(RGB signals), and uniformly tone-correcting respective colors of one same picture element based on the resulting signals of the said separation. CONSTITUTION:A lightness signal L from a lightness signal generating part(not shown in the figure) and A/D-converted three primary color signals (r), (g), and (b) are inputted to a tonal correction part 3 which executes the tonal correction. The part 3 consists of a table conversion part 10 and three pieces of multimpliers 11, 12, and 13 for the respective color signals; the levels of the lightness signals L inputted to the converter 10 are converted to a parameter (a) consisting of positive values centering at '1' that correspond to each of the levels. This parameter (a) and the A/D-converted three primary color signals (r), (g), and (b) are inputted to the multipliers 11, 12, and 13, and the results are outputted as tonal-corrected three primary color signals R, G, and B. That is, the parameter (a) corresponding to the levels of lightness signals L is respectively added with the three primary color signals (r), (g), and (b) by adder- subtractors 21, 22, and 23, and the tonal correction is executed with: R=(r)+(a), G=(g)+(a), and B=(b)+(a). Therefore, the three primary color signals (r), (g), and (b) can be tonecorrected in one same direction(plus direction or minus direction).
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