Automatic white balance control circuit

Abstract

Abstract PURPOSE:To obtain a stable control state in which a white balance state is not changed to a small decision error by controlling the white balance so as to maintain a previous previous white balance control state when a white balance error is below a prescribed threshold and reduce the error when the error exceeds the threshold. CONSTITUTION:A detecting means 24 for detecting a video signal position corresponding to an object low in a chroma of a color video signal, extracting means 8, 9 for extracting a color difference signal part corresponding to the video signal position detected by this detecting means from a color difference signal, integrating means 10, 11 for integrating the extracted signal and control means 17, 18, 20, 21 for outputting a constant control output when an output value from the integrating means 10, 11 does not exceed the threshold, outputting a control output to suppress it when it exceeds the prescribed threshold and controlling a gain to the three primary color signals are provided. Thereby, the correct white balance is obtained by the use of a picture signal to execute a white balance control influenced by the change of a picture with difficulty.

Inventors

• 👤 Takahiro Nakamura

Bibliographic Details