CMYK color model spot colors (such as metallic inks), and finishes such as varnish, which enhances the glossy appearance of the printed piece. CMYK are the process printers which often have a relatively small color gamut. Processes such as Pantone's proprietary six-color (CMYKOG) Hexachrome considerably expand the gamut. Light, saturated colors often cannot be created with CMYK, and light colors in general may make visible the halftone pattern. Using a CcMmYK process, with the addition of light cyan and magenta inks to CMYK, can solve these problems, and such a process is used by many inkjet printers, including desktop models. Comparisons between RGB
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,