forming a character - based monochromatic image from a digital representation of a color image by forming a character - based representation of the color image in which a plurality of color characters each describe the background and foreground color within a defined area of the color image , providing a plurality of color pattern masks each corresponding to a color in the color image and comprised of a pattern of light and dark dots capable of providing , in the monochromatic image , visual discrimination between areas of different color , transforming the color characters to monochromatic characters by replacing the background and foreground color of each color character with the corresponding pattern of light and dark dots , and displaying the monochromatic characters on a character - based output device .