PURPOSE: To improve the vertical resolution degree of a color sensor by providing each pixel line with at least one-type common color pixel and comparing the nth line common color pixel signal out of common picture pixel signals with the (n-1)th line common color pixel signal and the (n+1)th one.

CONSTITUTION: In terms of a signal processing circuit, the output signal of one hour delaying device 3 is inputted to a subtractor 6B. Difference signals VD and VU of respective signals inputted to 6A and 6B are inputted a comparator circuit 7, which switches the gate of a switching circuit 8 before the next color element bit signal is inputted to the switching circuit 8. An output signal SN-1 of the one hour delaying device 3 is inputted to an adder 4B and the switching circuit 8 through one bit delaying device 2C. The comparator 7 outputs "00", 10, 01 and 11 at the time of 1VD1>VU1, 1VD11VU1, 1VD1<1VU1 and 1VD1-1VU1, respectively and outputs four switching signals to the gate circuit 8 after delaying these signals by the prescribed period.