1. An image-processing apparatus for processing images, comprising: an image capture unit for acquiring image signals composed of multiple color components of a 2×2 color-coding array; a filter for calculating an average of pixel values of any (2n−1) pixels acquired from the image signals by the image capture unit, each of the acquired (2n−1) pixels including a target pixel and adjacent pixels having the same color component as that of the target pixel, and defining the average by averaging the adjacent pixels and the target pixel having the same color; and an extraction unit for extracting a pixel corresponding to the averaged adjacent pixels and the target pixel at an extraction rate of 1/(2n−1), wherein n comprises a positive integer value.