in Figure 2-4. Notice that in this drawing, the color opposite each primary
is the complement necessary to make white.
(You are looking through the overlapping filters at a
white light source behind them.)
You can think of these colors in two ways - either they are created by
adding primary colors to build up to white, or you can think of them as
being created by subtracting colors from white light. For instance, yellow
can be thought of either as red added to green, or as blue subtracted from