PURPOSE: To automatically execute emphasizing and smoothing processing at optimum degree even without allowing an operator to select a space filter by evaluating the quality of an objective image by fuzzy inference and executing the emphasizing or smoothing processing in accordance with degree correspond ing to the quality of the objective image.

CONSTITUTION: A fuzzy processor 4 extracts an objective image from an image storing device 3 and calculates the standard deviation of a pixel value for the objective image. A difference of data between a certain pixel and its adjacent one is also calculated. A processing degree determining means determines emphasizing or smoothing processing by fuzzy inference based upon the calculated standard deviation and the data difference. Namely the quality of the objective image which differs variously in accordance with measuring conditions is evaluated by fuzzy inference based upon its standard deviation and data difference, and after executing the normalization of the space filter, the emphasizing or smoothing processing is executed by the degree corresponding to the quality of the objective image. Thereby it is unnecessary for an operator to select the space filter.