1. An image processing system comprising: a noise detection unit extracting a local statistical characteristic of a predicted original image according to a local statistical characteristic of an observed image and a local statistical characteristic of a predicted noise image, setting a first flag level indicating a distortion state for each of pixels of the observed image according to the local statistical characteristic of the predicted original image, segmenting the observed image through a filter window, and detecting a noise by correcting the first flag level to a second flag level based on distortion states of adjacent pixels; and a noise removal unit removing the noise by adaptively setting a filter size according to the second flag level, when the second flag level is determined through the noise detection unit.