Patent ID: 8159566

Claim:
An apparatus for compensating signal distortion caused by noise, the apparatus comprising: a noise reduction unit which reduces noise of an input signal comprising zero mean random noise; and a signal compensator which compensates an output signal of the noise reduction unit which contains non-zero mean random noise left over after a noise reduction process performed by the noise reduction unit, the signal compensator compensates the output signal so that a signal distortion due to the non-zero mean random noise is removed from the output signal of the noise reduction unit, if illuminance of light input to the imaging device is lower than first threshold corresponding to an illuminance when a magnitude of the output signal of the noise reduction unit equals a standard deviation of the zero mean random noise, or if an illuminance of light input to the imaging device is higher than second threshold corresponding to an illuminance when if a magnitude of the output signal of the noise reduction unit equals a value obtained by subtracting a standard deviation of the zero mean random noise from a maximum signal magnitude, wherein the zero mean random noise is randomly distributed noise having a mean value of zero, and the non-zero mean random noise is randomly distributed noise having a mean value of which is not zero.