An image processing apparatus has a color image obtaining means configured obtain color image data representing a color image of biographic tissues, a lesion determining means configured to determine whether each pixel of the color image is of a lesion part based on the color image data, and a marking means configured to apply a mark indicating a position of the lesion part on the color image based on a result of determination, and the mark is configured such that the color image at a background of the mark can be seen.