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

Color vision deficiency (CVD), more commonly known as color blindness, is a visual impairment that affects a person's ability to perceive certain colors or distinguish between them. It occurs when the specialized cells in the retina of the eye, called cones, which are responsible for detecting different wavelengths of light and allowing us to see colors, do not function correctly. This can be due to genetic factors or acquired conditions.
   
The most common types of color blindness are called protanomaly, deuteranomaly, and tritanomaly. These terms refer to the affected type of cone cell in the retina which results in reduced sensitivity to one of the primary colors of light. You will explore a simulation of each of these types of color vision below and guess which cone is affected in each condition.
   
Color blindness is usually an inherited condition caused by genetic mutations on the X chromosome. Since males have only one X chromosome (XY), they are more likely to be color blind than females, who have two X chromosomes (XX). However, females can still be carriers of the genetic mutation and pass it on to their children.
   
Color blindness can lead to difficulties in distinguishing between certain colors, particularly those that are affected by the specific type of color vision deficiency. For example, a person with red-green color blindness may have trouble differentiating between shades of red and green, seeing them as similar or indistinguishable. Blue-yellow color blindness is rarer and can cause confusion between shades of blue and green or between blue and yellow colors.
   
While there is currently no cure for color blindness, people with this condition can adapt and learn to recognize colors based on their brightness or other visual cues. In some cases, special assistive technologies or color-correcting lenses may help enhance color perception for certain individuals. However, the extent of improvement varies from person to person. It's important to note that most individuals with color blindness can lead normal, fulfilling lives and adapt to their visual challenges with the help of various strategies and support.

Using Maple, we can simulate the effect of CVD on the perception of a sample color palette plotted in the RGB color space. Select a CVD type, and then slowly increase the severity from 0 to 100 and watch as the colorspace is distorted and each color in the palette changes. You may find it useful to rotate the plots as you increase the severity. If you personally experience a form of color blindness, you can still describe the effect of the simulation as the points representing the colors in the gamut contract into a plane. You should also recall what property is plotted along each axis.

(a) For each type of color blindness, which cone do you believe is affected?

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.