Automatic white balance control apparatus capable of performing white balance with a subject of a monochromatic color other than white

Claim 1

An automatic white balance control apparatus characterized by comprising: analog-to-digital conversion means for successively sampling each of two color information components contained in a video signal and for converting each sampled component into digital color information data; quadrant determination means for determining to which quadrant of a coordinate system coordinates defined by the two color information components at a current sampling instant belong, the coordinate system being two-dimensional and having coordinate axes corresponding respectively to said two color information components, said quadrant determination means generating a quadrant signal representative of the determined quadrant; difference forming means for forming, with respect to each of the two color information components, difference data between color information data at the current sampling instant and the color information data at an instant which is shifted a predetermined number of samples from said current sampling instant; accumulation means for accumulating, over the video signal corresponding to at least one picture, each of the two color information data and the two difference data with regard to each quadrant of said coordinate system in accordance with said quadrant signal; data processing means for comparing, with respect to each of the two color information components, the accumulated values of the color information data in the respective quadrants of said coordinate system with each other after applying respectively thereto weights which are dependent on the accumulated values of the difference data relative to the corresponding color information data in the respective quadrants, and for generating a control signal which is dependent on result of the comparison; and gain control means responsive to the control signals corresponding respectively to the two color information components for controlling gains for these color information components.