in order to provide an image processing device and the like making it possible to generate a target image in which edges of a structure are upheld and from which streaking artifacts are removed , a computation device determines a shape of a non - linear function on the basis of feature amounts of an original image and a smoothed image . next , the computation device calculates a condition coefficient of the original image and the smoothed image by using the non - linear function for which the shape was determined in s 101 . next , the computation device uses the condition coefficients calculated in s 102 to calculate a weighting coefficient for each of the pixels of the original image and the smoothed image . next , the computation device adds weighting to the original image and the smoothed image to generate the target image .