An image display apparatus having a computer system and an image processor. The computer system includes: a personal computer having a CPU and a main memory; and input/output apparatuses such as magneto-optical disk drive, image scanner, full color printer, etc. The image processor which commonly uses a system bus of the computer system includes an independent dedicated image bus, a compression/expansion unit, an image memory read/write controller, image memories, and a video processor. Image data which is sent from the magneto-optical disk drive is decoded by the compression/expansion unit and is held in the image memories. The image data of the image memories is transferred to the video processor through a dedicated signal line and is displayed on a large screen projection display.