Color reflected color depends upon the viewing angle. Numerous scientists have carried out research in butterfly wings and beetle shells, including Isaac Newton and Robert Hooke. Since 1942, electron micrography has been used, advancing the development of products that exploit structural color, such as "photonic" cosmetics. Color Color (American English), or colour (Commonwealth English), is the characteristic of human visual perception described through color "categories", with names such as red, orange, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the visible spectrum. Color categories and
Judo in Canada (2011), Raymond Damblant (2012), and Hiroshi Nakamura (2012). Eleven Canadians are ranked "hachidan" (eighth dan), twenty-seven are ranked "shichidan" (seventh dan), and approximately 85 others are ranked "rokudan" (sixth dan). The names of the ninth and eighth "dan" holders are listed in the tables to the right. A typographic dagger () follows the names of those who are deceased. A registry of approximately 5000 black belts ranked "shodan" (first "dan") to "hachidan" (eighth "dan") in the years 1946–1997 is included in Glynn Leyshon's book "Judoka: a history of Judo in Canada". Canadians have won five Olympic medals in Judo since