A different kind of rainbow
Human color vision depends on three types of photoreceptor cells in the retina known as cones. These S-, M-, and L-cones are each sensitive to different wavelengths of light—short (blue), medium (green), and long (red), respectively. The brain interprets the relative signals from these three cone types to perceive a spectrum of up to one million colors. Tritanopia is a form of color vision deficiency where the short-wavelength S-cones are missing or non-functional. This eliminates the ability to perceive the blue-yellow spectrum.
This condition is rare, affecting fewer than 1 in 10,000 people. Unlike the more common red-green color blindness, which is an X-linked recessive trait affecting more men, tritanopia is an autosomal condition. It results from a mutation on chromosome 7, meaning it affects males and females at equal rates. People with tritanopia have dichromatic vision; their world is painted with reds, greens, and greys. They typically confuse blue with green, yellow with violet, and yellow with pink. While congenital tritanopia is a stable, lifelong condition, an acquired form can result from head trauma, alcoholism, or age-related changes to the eye's lens.
The artist's eye
The diagnosis of historical figures is speculative, but some art historians and ophthalmologists suggest certain artists may have had a form of color vision deficiency. The 19th-century French artist Charles Meryon is a notable example. Born in 1821, Meryon initially pursued a career as a painter. He soon realized he had a color vision defect and abandoned painting in favor of etching, a medium that depends on line and contrast rather than color. Meryon's etchings, especially his famous series of Parisian cityscapes from 1850 to 1854, are known for their dramatic use of light and shadow, conveying a moody and gothic vision of the city. His one known oil painting, "Ghost Ship," shows a preference for blues and yellows, which some researchers suggest is typical for artists with this specific color vision defect trying to work with colors they perceive differently. His personal struggles were immense; he suffered from mental illness and died in an asylum in 1868.
The work of artists with any form of color vision deficiency shows alternative sensory worlds. Their canvases are not "wrong"; they are accurate representations of their distinct perceptual reality. For these artists, a limited palette is not a limitation but a different set of rules, forcing a reliance on tone and composition to convey emotion and form.