One aspect of embodiments of the present invention relates to an image processing apparatus which specifies one of boundary positions of retina layers in a fundus image showing a retina tomosynthesis, sets a distance transfer function for converting the distance from the specified boundary position to a parameter expressing opacity such that the peak position of the opacity is set to a predetermined position in the retina, sets a luminance transfer function for converting a luminance value of the fundus image to the parameter expressing opacity, and generates a translucent display image by calculating the opacity of respective positions of the tomosynthesis using the distance transfer function and the luminance transfer function, and by volume rendering.