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
Orange (colour) Orange is the colour most easily seen in dim light or against the water, making it, particularly the shade known as safety orange, the colour of choice for life rafts, life jackets or buoys. Highway temporary signs about construction or detours in the United States are orange, because of its visibility and its association with danger. It is worn by people wanting to be seen, including highway workers and lifeguards. Prisoners are also sometimes dressed in orange clothing to make them easier to see during an escape. Lifeguards on the beaches of Los Angeles County, both real and in television