Epson Stylus Photo 700 User Manual page 191

Process of color printing
A printer produces color images by printing tiny patterns of ink dots
using CMYK colors as mentioned in the previous section. Because most
ink jet printers are not able to print different gradations of the three
primary colors, they must use a halftoning method in order to represent
millions of colors or the gradation of colors as follows:
Dithering and error diffusion are the most commonly used halftoning
methods.
Dithering
Dithering uniformly aligns individual dots of different colored inks to
create the appearance of neutral colors. This method is suitable for
printing documents that contain large areas of solid color, such as bar
charts and graphs.
Error diffusion
Error diffusion randomly places individual dots of different colors to
create the appearance of neutral colors. By randomly placing dots, the
printer can achieve excellent colors and subtle color gradation. This
method is suited for printing documents that contain finely detailed
graphics or photographic images.
A-4
Tips for Color Printing