Abstract: A method for initializing a counter within a corresponding set of A/D converters of N sets of A/D converters of a single-chip CMOS-type image sensor in order to minimize none uniformity across the N sets of A/D converters is provided. The single chip CMOS type image sensor includes an image sense array having N columns of output lines for outputting N analog signals respectively; and a signal process device for generating N sets of digital signal each of which corresponds to one of N analog signals respectively. The signal process device has N input lines and N sets of A/D converter each of which including a counter for generating one of the N sets of digital signal respectively. The method comprises the steps of applying a predetermined reference voltage at each of N input lines of the signal process device such that a compensation value corresponding to each set of A/D converter is obtained.