1. An image-processing method, comprising: in an image-processing device: modifying, based on a first signal pattern, adjusted pixel values of at least one pixel in a region of a multi-channel image to generate modified pixel values; computing a pixel difference value based on a difference between said adjusted pixel values and said modified pixel values of said at least one pixel in said region; determining, a score based on: a ratio of said pixel difference value and a maximum pixel step value that corresponds to said modified pixel values; and said maximum pixel step value that exceeds a threshold noise level for said region; and suppressing, false color in said region of said multi-channel image, based on said score.