PURPOSE: To make many hue expressions possible and obtain a uniform color picture without color variance, by leading a color difference signal and a luminance signal from a CCD sensor and converting them to digital signals in an AD converter.

CONSTITUTION: A signal W is outputted from a CCD sensor 1 and is inputted to a sample holding circuit 12 through an analog gate circuit 11. This signal is inputted to an A-D converter 14 by an analog gate circuit 13 and is converted to a digital signal. This signal is separated as a luminance signal by a digital gate circuit 15. Next, a signal C is outputted from the CCD sensor 1, and the circuit 11 is switched to input this signal to a differential amplifier 16. The amplifier 16 operates a signal of a difference W-C between the signal C and the signal W held in the circuit 12 and inputs this differential signal to the converter 14 through the circuit 13. This color diference signal W-C is converted to a digital signal and is separated as the first color difference signal S1 by the digital gate circuit 15. This operation is repeated to obtain the luminance signal and the first and the second color difference signals S1 and S2.