A photoreceptor composed of bacteriorhodopsin and 6-nitro spiropyran was fabricated for the enhancement of the ratio of signal to noise. Bacteriorhodopsin, a protein generating photocurrent, was deposited onto the pretreated ITO glass using LB technique and its photoelectric effect was verified. The photocurrent generated by bacteriorhodopsin was proportional to the light intensity change. The other side of the glass was used as a substrate for the deposition of synthesized spiropyran by the spin coating technique. The spiropyran film fabricated by the spin coating technique showed its native optical property, photochromism. In the constructed photoreceptor, the increment of the intensity ratio of transmitted light in comparison with that of input light was obtained when two input lights of different light intensity were irradiated onto the films. Depending on the intensity of transmitted light, the photocurrent was generated by bacteriorhodopsin LB films. By this process, the ratio of output photocurrent generated by the transmitted light could be obtained, which can be applied to the construction of the image sensor to extract the desired image. The extraction efficiency of the proposed photoreceptor was about 25% with 40 min of extraction time.