| 摘要 |
PURPOSE:To make it possible to adjust white automatically, by utilizing facts that the color difference signal becomes zero for picking-up of a white object and primary color signals become equal to one another for it. CONSTITUTION:The G signal from input terminal 111 is applied to the noninversion input terminals of comparing circuits 117 and 118 after averaged by low-pass filter 116. Meanwhile, R and B signals from terminals 3 and 4 are applied to inversion input terminals of comparing circuits 117 and 118 after averaged by low-pass filter 116. The average level of the R signal and the average level of the B signal are compared with the average level of the G signal in comparing circuits 117 and 118, and these difference outputs are counted by reversible counters 50 and 51. Count values are converted to voltages by D/A converters 60 and 61, and the gain of variable gain amplifiers 5 and 6 is controlled by these voltages, thereby equalizing the amplitude of respective primary color signals. |
