Television – Image signal processing circuitry specific to television – Color balance or temperature
Reexamination Certificate
1998-03-13
2001-02-06
Miller, John W. (Department: 2711)
Television
Image signal processing circuitry specific to television
Color balance or temperature
C348S221100, C348S224100, C348S229100, C348S230100
Reexamination Certificate
active
06184940
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an imaging apparatus for use in a video camera and more specifically to an imaging apparatus capable of separately adjusting the white balances for two subjects of different color temperatures.
2. Description of the Prior Art
Conventional imaging apparatuses used in video cameras have only one white balance control system. In such imaging apparatus, the adjustment of white balance is achieved by adjusting the sensitivity of color channel amplifiers in response to the averages of color difference signals. However, there may be more than one subject of different color temperatures (like indoor and outdoor) in a view. If the white balance is adjusted in preference to an indoor portion of the image, the white balance will not be maintained in outdoor portion(s) and vice versa.
Thus, a need exists in the art for an imaging apparatus capable of adjusting both of the white balances for different color temperatures.
SUMMARY OF THE INVENTION
The above and other needs are met by an imaging apparatus capable of separately adjusting white balances for a long exposed image portion and a shortly exposed image portion in which a signal obtained through a long exposure (hereinafter, referred to as a “long exposed signal”) and a signal obtained through a short exposure (hereinafter, referred to as a “shortly exposed signal”), respectively are synthesized into a luminance signal, a first color difference (referred to as “CD”) signal (e.g., R−G), and a second CD signal (e.g., B−G) to yield a video signal and in which the shortly exposed signal has been modulated by one of four colors. The imaging apparatus at least comprises: a microcontroller comprising a microcomputer; a multiplier for multiplying the magnitude of each pixel value in the shortly exposed signal by one of four gains (prepared for the four colors) associated with the modulation color; and a multiplier for multiplying the magnitudes of a first one (R in this example) and a second one (B in this example) of three primary colors which are unique components of the first and second CD signals by first and second gains, respectively. The microcontroller provides, substantially for each field, a signal indicative of one of long and short modes. In each field of the short mode, the controller finds the four gains to adjust the magnitude of the shortly exposed signal such that at least one of an average of the first CD signal and an average of the second CD signal converges on a predetermined target value. In each field of the long mode, the controller finds the first and second gains to adjust the magnitudes of the first color (R) and a second color (B), respectively, such that said at least one of said averages converges on the predetermined target value.
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Gopstein Israel
Matsushita Electric - Industrial Co., Ltd.
Miller John W.
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