The present invention allows the positional relationship among a plurality of image
layers constituting a composed image to be precisely recognized. More specifically, the present invention is directed to an image composition
processing apparatus which generates a composed image which is a superposition of a plurality of image
layers and displays it within a window of the screen. When the user designates one of the image
layers and moves the pointer into the displayed composed image, the image composition
processing apparatus converts only a predetermined area of the image layers above the designated
image layer, for example, the area which is superposed in the range of a
radius of m picture elements centering the coordinate of the pointer in the composed image, to a translucent state. When the image composition
processing apparatus superposes the image layers a part of which is made translucent, a composed image which indicates to the user what position do the image layers above the designated
image layer take with respect to those below the designated
image layer in the periphery of the pointer is obtained.