| 摘要 |
PURPOSE:To adjust a white balance accurately without being affected by the brightness level of a subject by deciding the brightness level of the subject and opening and closing a feedback loop for color temperature control. CONSTITUTION:When switch circuits 20 and 21 are connected to output sides of comparators 16 and 18, the same operation with conventional circuits is carried out. When the level of a Y signal exceeds a reference level set with a variable resistor 25, the output of a comparator 22 goes up to a level H and the switch circuits 20 and 21 are connected to reference power sources 23 and 24. At this time, voltages of the reference power sources 23 and 24 are set corresponding to preset color temperature, so gains of gain control circuits 7 and 8 are so set as to obtain the preset color temperature for a subject having high brightness higher than some level. Consequently, an accurate while balance is obtained without being affected by the brightness level of the subject.
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