A method of removing noise from image data output from an image sensor includes comparing a target block in the image data with each of at least one comparison blocks around the target block in the image data. A center pixel similarity between center pixels of the target block and each comparison block is calculated. A neighboring pixel similarity between neighboring pixels neighboring the center pixels in the target block and each comparison block is calculated. The method includes determining whether an impulsive noise exists in the center pixel of the target block based on the center pixel similarity and the neighboring pixel similarity. A weight applied to a value of the center pixel of each comparison block is adjusted based on a result of the determining. Weighted averaging is performed on values of the center pixels of the comparison blocks to estimate a value of the center pixel of the target block.