White balance auto control circuit

Abstract

Abstract PURPOSE:To substantially reduce color blurring in case an object including the part of strong chroma is photographed by providing 1st and 2nd nonlinear amplifier circuits at a stage anterior to 1st and 2nd mean circuits averaging color difference signals and compressing the color difference signals whose amplitudes exceed a reference. CONSTITUTION:The 1st and 2nd nonlinear amplifier circuits 16 and 17 are provided between a 1st mixing circuit 8 and the 1st mean circuit 12 and between a 2nd mixing circuit 9 and the 2nd mean circuit 13, respectively. Since the 1st nonlinear amplifier circuit 16 compresses the color difference signals whose amplitudes exceed the reference, the R-Y color difference signals whose large amplitudes are compressed are inputted to the 1st mean circuit 12, and a gain is controlled so that the mean of the R-Y color difference signals can be zero. As for the waveform of the R-Y color difference signal whose white is balanced after the control of white balance, the part of weak chroma of the object R3 is balanced at a red point, and the part of the white object W is less mixed with cyan. The 2nd nonlinear amplifier circuit 17 improves a B-Y color difference signal just like the R-Y color difference signal.

Inventors

• 👤 Kanji Mikuni
• 👤 寛司 三国

Bibliographic Details