Automatic white balance correcting device

Abstract

Abstract PURPOSE:To execute an excellent automatic white balance adjustment even when illuminating light does not approximate Plank's law of radiation by detecting a difference between two color difference signals, and selecting one of plural reference voltages preliminarily set depending on whether the result of said difference is positive or negative. CONSTITUTION:The difference between the color difference signals (R-YL), (B-YL) is detected by an R-B detection circuit 16, and a signal (R-B) is generated as a first signal. A comparator/amplifier 17 compares this signal (R-B) with a first reference voltage Vref1. A switching circuit 18 switches between a second and a third reference voltages Vref2, Vref3 corresponding to the 'H'-level and 'L'-level of an output from the comparator/amplifier 17 and outputs respectively. An averaging circuit 19 averages outputs from the circuit 18. When the color temperature of the illuminating light is low, a value close to the second reference voltage Vref2 is taken, but as the color temperature raises, a value closer to the third reference voltage Vref3 is taken. As a result, even when the illuminating light does not approximate Plank's law of radiation, an excellent white balance adjustment can be executed.

Inventors

• 👤 Kenji Hisama

Bibliographic Details