Abstract: An image processing method for converting the pixel value of a pixel of interest in a displayed image, wherein pixel values of the pixel of interest and pixels surrounding the same are compared with a predetermined threshold value while a conversion characteristic most suitable for the pixel of interest is selected on the basis of the result of comparison indicating the magnitude relationship, and the pixel value of the pixel of interest is changed according to the most suitable conversion characteristic that is selected. The threshold may have different values for different pixels, may have the same value over one scan line, or may be constant for all pixels.

Abstract: A data interpolation processing apparatus used in an ultrasonic diagnostic system and having an interpolation arithmetic unit for obtaining indication data related to a point of interest using a total of eight sampling data. The eight sampling data are located on a total of four scanning lines which include two scanning lines placed on each of opposite sides of the point of interest in the scanning direction, and which include two sampling data on each of the four scanning lines, wherein each of the two sampling data are placed on the opposite sides of a line extending in the scanning direction and passing through the point of interest.