| | handprint : do "primary" colors exist? |
 | | All the 18th century color wheel authors resolved this issue in terms of tonal gradation, placing either pure fl or white paint at the center of the color wheel, mixtures of the primary colors around the circumference, and steps from the primary mixtures toward the center as increasing quantities of white or fl paint. |
 | | Nearly a century of research was necessary to confirm the existence of these color receptors in the retina by microscopic dissection of retinas in 1828, the isolation of the rod's photopigment (visual purple) in 1877, and detailed color mixing experiments in the late 19th and early 20th centuries. |
 | | Color matching data, repeated and varied across hundreds of different color samples and viewing situations for both normal and color deficient viewers, and archived in the color vision literature with light sensitivity and hue cancellation data, represent the ultimate sacred texts of color research. |
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