Patent ID: 7492391

Claim:
A method for generating wide dynamic range image in video cameras having an image sensor capable of readout of externally specified partial frames, comprising the following steps: configuring said image sensor to expose and readout a base frame; applying a low-pass filter to dark areas of the base frame; compressing base frame pixel range from 0 to TH1 into range 0 to TH2 and stretching pixel range from TH1 to ADCmax into range from TH2 to ADCmax, wherein TH1 is a parameter where pixels above TH1 are oversaturated and wherein ADCmax is the maximum bit value of ADC output and wherein TH2 is a parameter where TH2<TH1; determining rectangular image areas (windows) enclosing largest oversaturated base frame areas; storing the base frame in an image buffer memory; configuring said image sensor to sequentially expose and readout said windows; compressing the pixel range in each readout window from t w *TH1/t 0 ADCmax into range TH2 to ADCmax, wherein said t w is an optical integration time of a current window and said t 0 is an optical integration time of said base frame; and replacing in said image buffer memory base frame pixels with luminance values greater than TH2 with corresponding pixels from said windows.