By the end of this lesson, students will be able to:

With the Maple command WavelengthToColor in the ColorTools package we can convert the wavelength of visible radiation in nanometers (nm) to a color.  Below we use this command to generate an interactive plot.  By changing the wavelength with the slider, you can observe the change in color of the visible light.

First we unassign the variable λ

Second we make the interactive plot:

Slide the slider along the wavelength axis to explore the range of colors that can be produced via monochromatic light, which is a single source of light at a discrete wavelength.

(a) What is the wavelength, with units, of your favorite color?

The plot below shows the wavelengths at which each cone cell absorbs.

(b) Using the plot below, determine which cones in your eye absorb at the wavelength of your favorite color you recorded above. Note that for except at the very edges of your color vision, most wavelengths of light will be absorbed by multiple cones.

If your favorite color is in the purple-magenta-pink range, you should note that these colors cannot be produced with monochromatic (light of a single wavelength) light. Instead, these colors are produced by triggering your blue (S) and red  (L) cones without triggering your green (M) cones. This can only be accomplished via mixing at least two light sources in the blue and red ranges.

Figure 1: Normalized absorption curves for the S, M, and L cones. Data plotted from Stockman, A., MacLeod, D. I., & Johnson, N. E. (1993).

1. Christie, R. The Physical and Chemical Basis of Colour. In Colour Chemistry. 2nd Ed. Royal Chemical Society: Cambridge. 2001. pp. 12-21.
2. Stockman, A., MacLeod, D. I., & Johnson, N. E. (1993). Spectral sensitivities of the human cones. Journal of the Optical Society of America, A, Optics, Image & Science, 10(12), 2491–2521.

Selection of Additional Readings and Resources

Baumann, U. https://www.colorsystem.com/?page_id=551 (accessed 2023-09-07).

       A webpage summarizing and visualizing the evolution of color systems and color spaces from Plato to CIELab and other modern-day models.

Buether, A.; Augsburg, A.; Venn, A. In Colour: Design principles, planning strategies, visual communication; Institut für Internationale Architektur-Dokumentation, 2014; pp 33–37.

        A chapter on color systems and color spaces and their importance in art and designer from the perspective of a designer.

Ciechanowski, B. Color Spaces – Bartosz Ciechanowski. https://ciechanow.ski/color-spaces/ (accessed 2023-09-07).

       An interactive webpage by Bartosz Ciechanowski that explores the technical aspects of how additive color (colored light) can be mapped onto the RGB colorspace for use in screens.

Coblis - Color Blindness Simulator. https://www.color-blindness.com/coblis-color-blindness-simulator/ (accessed 2023-09-07).

       An interactive webpage that simulates various types of colorblindness for those of us with standard color vision. See if you can guess which cone cell type might be affected for each type of vision.