In this Exhibit: You push the red bottom to turn on the white light. Slide the color plates to see how the combination of two subtractive primary colors results in an additive primary color.
For better observation, look at the light projected on the ceiling.
Subtractive primary colors are important in the mixing pigments in paint or ink, in color printing, color photography and overlapping multiple filters.
As you have seen in additive mixing color demonstration, the white light can be thought as the sum of the three additive primary colors Red, Green and Blue. However, when a filter or colored pigment is illuminated by white light, we can observe:
a) When white light impinges on a subtractive color filter, one of primary colors is absorbed
b) Similarly, when white light shines on a subtractive colored pigment, the diffused light that is reflected has one of the additive primaries missing.
Cyan, Magenta and Yellow are the subtractive primary colors. Each one absorbs one of additive primary colors : Cyan absorbs Red, Magenta absorbs Green and Yellow absorbs Blue.
Adding two subtractive primary colors filters together will transmit one of the primary additive colors.
Adding all three subtractive primary color filters together will absorb all the colors of the white light spectrum as shown below.
Each filter (or pigment) absorbs its complementary color and transmits (diffusely reflects) the others.
1. Yellow filter absorbs Blue light and transmits Red and Green light. Red and Green light together are seen as Yellow.
2. Magenta filter absorbs Green light and transmits Red and Blue light. Blue and Red light together are seen as Magenta.
3. Cyan filter absorbs Red light and transmits Blue and Green light. Blue and Green light together are seen as Cyan.
Combining two of subtractive primaries filters obtains an additive primary color.
1. White light => Yellow filter + Magenta filter = Red light
2. White light => Yellow filter + Cyan filter = Green light
3. White light => Magenta filter + Cyan filter = Blue light