| 摘要 |
<p>A gradation corrector for use in a television receiver which can subject a signal at any luminance level to non-linear correction to provide optimum image quality. Memory (8) stores therein luminance histogram of an input signal. On the basis of the data, a circuit (33) detects a total frequency, a circuit (34) detects luminance distribution, and a circuit (35) detects the expanse of the luminance distribution. A circuit (36) calculates a fixed value to be added. Further, a circuit (38) detects a minimum luminance level, and a circuit (32) detects an average luminance level. A circuit (39) calculates an accumulation starting point and a circuit (40) calculates an accumulation stopping point. An adder (37) adds the calculated fixed value to the data in the memory (8). A circuit (9) accumulates the results in the range from the accumulation starting point to the accumulation stopping point. The accumulation result is stored in memory (10). A circuit (41) detects the maximum cumulative value, and a circuit (11) normalizes all the data stored in the memory (10) by use of this maximum value. The normalized data are stored in a memory (12). Thus, the input signal is subjected to optimum normalization by use of the normalized data. <IMAGE></p> |
