Lecture 4 --- 6.837 Fall '98

Color Printing

Green paper is green because it reflects green and absorbs other wavelengths. The following table summarizes the properties of the four primary types of printing ink.

dye color	absorbs	reflects
cyan	red	blue and green
magenta	green	blue and red
yellow	blue	red and green
black	all	none

To produce blue, one would mix cyan and magenta inks, as they both reflect blue while each absorbing one of green and red. Unfortunately, inks also interact in non-linear ways. This makes the process of converting a given monitor color to an equivalent printer color a challenging problem.

Black ink is used to ensure that a high quality black can always be printed, and is often referred to as to K. Printers thus use a CMYK color model.

Lecture 4

Slide 13

6.837 Fall '98