CMYK color model of the primaries: cyan and yellow produce green, cyan and magenta produce blue, yellow and magenta produce red (these subtractive secondary colors correspond roughly to the additive primary colors), plus layering all three of them resulting in black. With halftoning, a full continuous range of colors can be produced. To improve print quality and reduce moiré patterns, the screen for each color is set at a different angle. While the angles depend on how many colors are used and the preference of the press operator, typical CMYK process printing uses any of the following screen angles: The "black" generated by
Natural Color System more colors (184 light colors and 16 in the blue-green space) were added, adding to the current 1950 colors in the NCS 1950 standard colors. Colors that have a representation in the NCS 1950 samples are denoted with a leading capital "S", for example NCS S 1070-Y10R (a chromatic, slightly reddish yellow). The most important difference between NCS and most other color systems resides in their starting points. The aim of NCS is to define colors from their visual appearance, as they are experienced by human consciousness. Other color models, such as CMYK and RGB, are based on an understanding