An image processing apparatus, an image display system, an image processing method, and a program by which it is possible to grasp, on a screen for observing a given low-dimensional image having a lower level of dimensions than a medical image, information of the low-dimensional image in which a region of interest is present and information of the region of interest. A medical image including two or more low-dimensional images (102) is acquired, region-of-interest information representing information of a region of interest (108) automatically detected from the medical image is acquired for each of the low-dimensional images, axis information (104) representing a space axis or a time axis is generated, additional information (106) associated with the axis information is generated, the additional information including presence information indicating that the region of interest is present and content information indicating content of the region of interest, and the low-dimensional images, the axis information, and the additional information are displayed on a display.