Shades of green color standard is displayed at right. It is the color called green, low green or medium green in many of the older eight-bit computer palettes. Another name for this color is "green W3C". This is the X11/HTML color "dark green". The color defined as "green" in the CMYK color system used in printing, also known as "pigment green", is the tone of green that is achieved by mixing process (printer's) cyan and process (printer's) yellow in equal proportions. It is displayed at right. The purpose of the CMYK color system is to provide the maximum possible gamut of color reproducible
Green light source typically has a spectral power distribution dominated by energy with a wavelength of roughly 487570 nm. Human eyes have color receptors known as cone cells, of which there are three types. In some cases, one is missing or faulty, which can cause color blindness, including the common inability to distinguish red and yellow from green, known as deuteranopia or redgreen color blindness. Green is restful to the eye. Studies show that a green environment can reduce fatigue. In the subtractive color system, used in painting and color printing, green is created by a combination of yellow and blue,