White balance regulator of color video camera

Abstract

Abstract PURPOSE:To attain excellent color reproduction at any time by detecting the color temperature of a light source all the time and by automatically making corresponding white balance regulation. CONSTITUTION:Color video camera 1 is equipped with external photometry circuit 11 and its photodetector 12 consists of element R' responding strongly to short- wavelength light (specially, R component) and element B' responding strongly to long-wavelength light (specially, B component). The outputs of elements R' and B' to which scattering light from milk-white filter 16 is incident are input to logarithmic compressing circuits 131 and 132 and then R/B signal generating circuit 14 obtains the ratio of one signal to the other. Next, its R/B signal is supplied to white balancing circuit 15 to find a color temperature and an output that corresponds to the color temperature is supplied to R signal and B signal amplifying circuits 41 and 43 to change their gains according to the color temperature. Corresponding to the fluctuations of the color temperature, the white balancing circuit operates automatically, so that excellent color reproduction will come into effect at any time.

Inventors

• 👤 Kentaro Hanma
• 👤 Michio Ogimoto

Bibliographic Details