a method and apparatus is disclosed for independently displaying one of a plurality of images on a display and for superimposing the plurality of images onto one another to produce a composite image . one or more bit planes are selected to constitute a group , and one or more additional bit planes are selected to constitute another group . the number of groups corresponds to the number of images to be independently displayed . the priority of one group over the other is selected . this ensures that the image from the one group appears to be &# 34 ; in front of &# 34 ; the images from the other group on the display . in the case of a color terminal , the colors associated with each group are selected . a color map memory contains a plurality of brightness indices which determines image brightness . associated with each index is one or more color indices . the bits associated with each pixel are used as an index to the color map memory by locating the corresponding color indices . the associated brightness index is noted , and converted to an analog voltage for determination of image brightness . in response to the selection of the groups mentioned hereinabove , and the designation of priority among groups , the firmware recomputes the color map in the color map memory , that is , the color indices are set based upon the number of selected groups and the number of bit planes per group , and selected ones of the brightness indices are recomputed based on the designated priority among groups . due to the ability of the present invention to select one or more bit planes to constitute a group , and due to the firmware &# 39 ; s ability to recompute the color map , one or more images can be displayed on the crt , either independently of one another , or superimposed upon one another to produce a composite image .