Image superimposing apparatus having limited memory requirement

Claim 1

An image superimposing apparatus for superimposing a plurality of images to form one image for display, said image superimposing apparatus comprising: operation means for obtaining next image data related to a next frame based on present image data related to a present frame and differential image data of a plurality of images; memory means, coupled to said operation means to receive the next image data, said memory means including first and second banks each having regions and a memory capacity for storing at least one frame of image data, said memory means providing the present image data to said operation means; address generating means, coupled to said memory means, for generating a display address which is used to access said first and second memory banks when reading image data from said memory means for display; display control means, coupled to said address generating means, for storing display image numbers which distinguish the plurality of images in correspondence with the regions of each of said first and second banks, said display control means outputting a display image number in response to the display address from said address generating means; and bank control means, coupled to said display control means, for storing bank numbers of said first and second banks in correspondence with the display image numbers to indicate the one of said first and second banks from which the image data is presently being read out for display, said bank control means outputting a bank number in response to the display image number from said display control means, said display address from said address generating means and said bank number of said bank control means designating one of said first and second banks and its region from which the image data from said memory means is to be read out for display.