The human eye is sensitive to a narrow band of electromagnetic radiation that lies in the wavelength range between 400 and 700 nanometers, commonly known as the visible light spectrum, which is the only source of color. When combined, all of the wavelengths present in visible light, about a third of the total spectral distribution that successfully passes through the Earth's atmosphere, form colorless white light that can be refracted and dispersed into its component colors by means of a prism. The colors red, green, and blue are classically considered the primary colors because they are fundamental to human vision. Light is perceived as white by humans when all three cone cell types are simultaneously stimulated by equal amounts of red, green, and blue light.

The complementary colors (cyan, yellow, and magenta) are also commonly referred to as the primary subtractive colors because each can be formed by subtracting one of the primary additives (red, green, and blue) from white light. For example, yellow light is observed when all blue light is removed from white light, magenta forms when green is removed, and cyan is produced when red is removed. The color observed by subtracting a primary color from white light results because the brain adds together the colors that are left to produce the respective complementary or subtractive color.

Introduction - Pigments and dyes are responsible for most of the color humans see in the real world. Eyes, skin, and hair contain natural protein pigments that reflect the colors visualized in the people around us (in addition to any assistance by colors used in facial makeup and hair dyes). Books, magazines, signs, and billboards are printed with colored inks that create colors through the process of color subtraction. In a similar manner, automobiles, airplanes, houses, and other buildings are coated with paints containing a variety of pigments. The concept of color subtraction is responsible for most of the color produced by the objects just described. For many years, artists and printers have searched for substances containing dyes and pigments that are particularly good at subtracting specific colors.

Primary Additive Colors - Light is perceived as white by humans when all three cone cell types are simultaneously stimulated by equal amounts of red, green, and blue light. Because the addition of these three colors yields white light, the colors red, green, and blue are termed the primary additive colors. This tutorial explores how the three primary additive colors interact with each other, both in pairs or all together.

Primary Subtractive Colors - The complementary colors (cyan, yellow, and magenta) are also commonly referred to as the primary subtractive colors because each can be formed by subtracting one of the primary additives (red, green, and blue) from white light. This tutorial explores how the three primary subtractive colors interact with each other, both in pairs or all together.

Color Filters - Examine how color filters operate to change the color of objects visualized under filtered illumination. The tutorial enables visitors to drag and drop red, green, and blue virtual color filters over objects illuminated both with white light and also previously filtered with one of the primary additive colors.

Color Separation - Pigments and dyes are responsible for most of the color that humans see in the real world. Books, magazines, signs, and billboards are printed with colored inks that create colors through the process of color subtraction. This interactive tutorial explores how individual subtractive primary colors can be separated from a full-color photograph, and then how they can be reassembled to create the original scene.

Reference Listing - Presented in this section are selected literature references on various topics concerning both the additive and subtractive primary colors from our extensive library. The perception of color in the human visual system, whether in paint, printed materials or video displays depends on the interactions between the primary colors. Included are references to books and review articles that discuss numerous aspects of color theory and how they may be applied.

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