Automatic white balance control system for a color video camera

Claim 1

An imaging apparatus comprising: imaging means for converting an image into a plurality of color signals each having a signal level; white balance amplifier means, including at least first and second amplifiers for amplifying respective color signals, coupled to said imaging means, for adjusting the signal level of said plurality of color signals to produce a plurality of amplified color signals; calibration means for calibrating said white balance amplifier means and for producing at least one calibration parameter defining an automatic tracing white balance (ATW) control area which substantially tracks a black body radiation pattern, and is shifted with respect to intermediate gain values of said first and second amplifiers in accordance with results of an automatic white balance (AWB) measurement; detecting means, coupled to said white balance amplifier means, for detecting said plurality of amplified color signals; calculation means, coupled to said detecting means, for calculating, in an ATW operation, at least one white balance amplification adjustment as a function of said plurality of amplified color signals; comparing means for comparing said at least one white balance amplification adjustment with said at least one calibration parameter; and automatic adjustment means for automatically adjusting said white balance amplifier means to amplify the signal level of at least one of said plurality of color signals if said at least one white balance amplification adjustment is within said shifted ATW control area, and not adjusting said white balance amplifier means if said at least one white balance amplification adjustment is outside said shifted ATW control area.