White balance adjusting apparatus for automatically adjusting white balance in response to a color information signal obtained from an image sensing device

A white balance adjusting apparatus for automatically adjusting white balance based on color information signals of an image, comprising:

• means for amplifying red and blue signals, contained within the color information signals, with a corresponding variable gain so as to yield amplified color information signals;
• means for converting said amplified color information signals into a plurality of color difference signals;
• means for dividing each of the plurality of color difference signals into a plurality of regions;
• means, responsive to said dividing means, for integrating respective values of each of the plurality of color difference signals so as to convert the respective values of color difference signals into a plurality of color evaluating values corresponding to each one of the regions;
• means, responsive to each of the color evaluating values of each of said regions, for calculating a picture color evaluating value of the entire image for each one of the color information signals;
• means for controlling the variable gain in response to said picture color evaluating value, said means for controlling including
• means for varying a rate of change of the variable gain in response to a size of a portion of the image, said portion of the image containing individual ones of said regions wherein for each one of said individual ones of said regions, an amount of fluctuation between corresponding color evaluating values for said each one of said regions and an adjacent one of the regions is less than a reference value.

In an imaging apparatus having an image sensor with a color separating circuit receiving a photo-electric signal and producing green, red, and blue signals based on the photo-electric signal, a first adjustable gain amplifier providing an amplified first color signal based on a first one of the red, blue, and green signals produced by the color separating circuit and a gain control input, a second adjustable gain amplifier providing an amplified second color signal based on a second one, differing from the first one, of the red, blue, and green signals produced by the color separating circuit and a gain control input, and a camera processing circuit provided with a third one, differing from the first and second ones, of the red, blue, and green signals from the color separating circuit, the amplified first color signal from the first adjustable gain amplifier, and the amplified second color signal from the second adjustable gain amplifier, and producing a luminance signal, a first color difference signal, and a second color difference signal, a white balance adjusting apparatus for automatically adjusting white balance in response to the first and second color difference signals produced by the camera processing circuit, the apparatus comprising:

• a) a selector for selecting the luminance signal during a first time period, the first color difference signal during a second time period, and the second color difference signal during a third time period;
• b) an integrator for dividing the one of the luminance signal, the first color difference signal, and the second color difference signal selected by the selector into a plurality of regional digital signals based on a plurality of regions and summing each of the plurality of regional digital signals over a corresponding one of the first, second, and third time periods, to produce a plurality of regional luminance evaluation factors, a plurality of regional first color evaluation factors, and a plurality of regional second color evaluation factors during the first, second, and third time periods;
• c) a storage device for buffering the plurality of regional luminance, first color, and second color evaluation factors;
• d) an image evaluator for producing a first color evaluation factor based on the plurality of regional first color evaluation factors and for producing a second color evaluation factor based on a plurality of regional second color evaluation factors;
• e) a first color gain controller for providing a first gain control signal such that the first color evaluation factor will approach zero;
• f) a second color gain controller for providing a second gain control signal such that the second color evaluation factor will approach zero;
• g) a gain adjusting device for adjusting the first and second gain control signals based on a comparison of the color of all vertically and horizontally adjacent regions,
• wherein the first and second gain control signals, as adjusted by the gain adjusting device, are provided to the gain control inputs of the first and second adjustable gain amplifiers, respectively.