Patent ID: 7970234

Claim:
A post-processing circuit for processing an image signal formed of an original signal and noise components, the circuit comprising: a low-frequency extracting unit outputting a low-frequency image component of the image signal as a low-frequency signal; a high-frequency extracting unit multiplying a high-frequency image component of the image signal by a first gain and outputting the multiplication product as a high-frequency signal; an intermediate-frequency extracting unit multiplying an intermediate-frequency image component of the image signal by a second gain and outputting the multiplication product as an intermediate-frequency signal; and an adder adding the low-frequency signal, the high-frequency signal and the intermediate-frequency signal and outputting the addition sum as a post-processed signal, wherein the first gain and the second gain are set differently according to a pixel location in a spatial domain, and wherein the first gain is set to a first value that decreases the high-frequency image component if the energy of a noise component in a high-frequency image component is larger than an energy of a high-frequency component of the original signal, or the first gain is set to a second value that increases the high-frequency image component if an energy of the noise component is less than an energy of the high-frequency component of the original signal.