1. An image processing apparatus comprising: input means for entering image data; memory means for storing plural image patterns; comparator means for comparing the image data entered by said input means with the image patterns stored in said memory means; and smoothing means for smoothing said input image data according to the result of comparison by said comparator means, wherein said comparator means is adapted to vary the image patterns to be used in said comparison, according to a resolution of the image date entered by said input means, and wherein said memory means stores plural first image patterns corresponding to image date of a low resolution, and plural second image patterns corresponding to image date of a high resolution.