IMAGE SENSOR HAVING AUTOMATIC BLACK LEVEL COMPENSATION FUNCTION AND METHOD FOR COMPENSATING BLACK LEVEL AUTOMATICALLY

An image sensor having an automatic black level compensation function and an automatic black level compensation method are provided to reduce the number of lines for calculating a black level offset value and the number of lines for calculating an offset value on an analog signal processing path and reduce a dark pixel array disposed for detecting the offset value. A pixel array(110) has the first pixel group(111) and the second pixel group(112). The first pixel group(111) has real pixels for generating real pixel data. The second pixel group(112) has pixels for calculating the first offset value of a dark pixel. A test signal providing unit(130) provides a test signal for detecting the second offset value on an analog signal process. The first and the second selection units(120a,120b) select and output one of a dark pixel signal read from the second pixel group(112) and the test signal outputted from the test signal providing unit(130). The first and the second analog signal processing units(140a,140b) process the signals selected and outputted through the first and the second selection units(120a,120b). ADCs(Analog to Digital Converters)(150a,150b) convert the analog signals outputted from the first and the second analog signal processing units(140a,140b) into digital signals, and output the digital signals. A DSP(Digital Signal Processor)(160) calculates the first and the second offset values by using the digital signals outputted from the ADCs(150a,150b), and calculates the third and fourth offset values on the first and the second analog signal processing paths by using the first and the second offset values.