The image display method and apparatus display a monochromatic image with a color display device in which a unit pixel is composed of R, G and B cells and display the monochromatic image having a higher gradation resolution than reproduction performance of each of the R, G and B cells in the color display device. In the method and apparatus, input data of the monochromatic image to be displayed on the color display device is allotted to R, G and B data for the R, G and B cells, respectively and the R, G and B data of the monochromatic image obtained by allotment is output to the R, G and B cells for display on the color display device. The method and apparatus can display an increased number of gradations so that monochromatic images used in the medical field can be displayed in a sufficiently high definition to suit diagnostic purposes.