1. An image processing apparatus comprising: an edge detection part that detects an edge of a subject depicted within an input image; a luminance change determination part that determines whether a luminance value in a vicinity of the edge in the input image is increased or decreased in a predetermined direction from the edge; and a contour supplement part that supplements a contour to the edge in the input image, the contour having the luminance value changed over a period of time depending on a result of the determination, wherein the edge detection part, the luminance change determination part, and the contour supplement part are each implemented via at least one processor.