To create an image which is prevented from being emphasized in a negative direction even when high frequency components are emphasized by a high-pass filter.

An image emphasis processing method includes: a contrast emphasis step S01 for creating a contrast emphasized image by emphasizing the high frequency components of an original image by a high-pass filter; and an emphasized image creation step S02 of comparing the pixels values of the original image and the contrast emphasized image for each pixel, and selecting the larger pixel value between those respective pixel values to create an emphasized image. The pixel values of the original image and the contrast emphasized image are compared for each pixel, and the larger pixel value between those respective pixel values is selected so that it is possible to prevent the image from being emphasized in a negative direction.