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
Color printing are variously used in printing, the result should be a reasonable reproduction of the original, but in practice this is not the case. Due to limitations in the inks, the darker colors are dirty and muddied. To resolve this, a black separation is also created, which improves the shadow and contrast of the image. Numerous techniques exist to derive this black separation from the original image; these include grey component replacement, under color removal, and under color addition. This printing technique is referred to as CMYK (the "K" stands for "key", a traditional word for the black printing plate). Today's