Automatic white balance adjuster of color video camera


PURPOSE: To make adjustment simple and rapid, by regarding a part where luminance exceeds a specified level among photographed actual objects as white, and by making white balance adjustment by that signal. CONSTITUTION: A reflected light from an object 1 passed through a lens 2 is supplied to a pickup tube 3, this output signal is used as an electrical signal presenting brightness (Y) and electrical signals presenting color (R, B) through a signal processing circuit 4. These signals are inputted to a matrix circuit 7 and outputted as color difference signals R-Y, B-Y. Here, when the value of luminance signal is higher than a specific level, a part of color difference signal R-Y is attenuated and inputted to an input terminal of a comparator 13. When, for example, the output signal of the comparator 13 is high in level, an up-down counter 15 works as an up counter and counts the clock pulse, and at the same time it controls a variable gain amplifier 5 to reduce the gain through the D/A converter. Likewise, when the signal is low in level, it controls so that the gain may increase, resulting in good white balance. COPYRIGHT: (C)1986,JPO&Japio




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Patent Citations (1)

    Publication numberPublication dateAssigneeTitle
    JP-S51114823-AOctober 08, 1976Hitachi Denshi LtdHigh-level chromatkey system for color tv camera

NO-Patent Citations (0)


Cited By (5)

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    JP-H0294890-AApril 05, 1990Nec CorpWhite balance correcting circuit
    JP-H031790-AJanuary 08, 1991Canon IncImage pickup device
    JP-S62281069-ADecember 05, 1987Canon IncColor image processor
    JP-S62281070-ADecember 05, 1987Canon IncColor image processor
    JP-S62281071-ADecember 05, 1987Canon IncColor image processor