Cyan, magenta, yellow, and key (black).

Layers of simulated glass vividly show how semi-transparent layers of color combine on paper into spectrum of CMY colors.

CMYK (short for cyan, magenta, yellow, and key (black), and often referred to as process color or four color) is a subtractive color model, used in color printing, also used to describe the printing process itself. Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the acronym.^[1] Image File history File links CMYK_color_swatches. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Cyan (from Greek κυανοs, meaning blue) may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. ... Magenta is a color made up of equal parts of red and blue light. ... A yellow Tulip. ... This article is about the color. ... Subtractive color mixing An 1877 color photo by Louis Ducos du Hauron, a French pioneer of color photography. ... A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components (e. ... Color printing is the reproduction of an image or text in color (as opposed to simpler black and white or monochrome printing). ...

The CMYK model works by partially or entirely masking certain colors on the typically white background (that is, absorbing particular wavelengths of light). Such a model is called subtractive because inks “subtract” brightness from white. Color is an important part of the visual arts. ... The wavelength is the distance between repeating units of a wave pattern. ... Brightness is an attribute of visual perception in which a source appears to emit a given amount of light. ...

In additive color models such as RGB, white is the “additive” combination of all primary colored lights, while black is the absence of light. In the CMYK model, it is just the opposite: white is the natural color of the paper or other background, while black results from a full combination of colored inks. To save money on ink, and to produce deeper black tones, unsaturated and dark colors are produced by substituting black ink for the combination of cyan, magenta and yellow. Additive color mixing: adding red to green yields yellow; adding yellow to blue yields white. ... RGB redirects here. ... This article is about the book. ... It has been suggested that this article or section be merged with Chromaticity. ...

Halftoning

This close-up of printed halftone rasters show that magenta on top of yellow appears as orange/red, and cyan on top of yellow appears as green.

Main article: Halftone

With CMYK printing, halftoning (also called screening) allows for less than full saturation of the primary colors; tiny dots of each primary color are printed in a pattern small enough that humans perceive a single color. Magenta printed with a 20% halftone, for example, produces a pink color, because the eye perceives the tiny magenta dots and the white paper between the dots as lighter and less saturated than the color of pure magenta ink. Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... Left: halftone spots. ... Left: halftone spots. ... Left: halftone spots. ... Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. ...

Without halftoning, the three primary process colors could be printed only as solid blocks of color, and therefore could produce only six colors: the three primaries themselves, plus three complementary colors produced by layering two of the primaries—cyan and yellow produce green; cyan and magenta produce a purplish blue; yellow and magenta produce red (these subtractive complementary colors correspond roughly to the additive primary colors). With halftoning, a full continuous range of colors can be produced.

Screen angle

An image along with its cyan, magenta, and yellow components.

To improve print quality and reduce moiré patterns, the screens for individual colors are set at unique angles. While the specific 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:^[2][3] Image File history File linksMetadata Download high-resolution version (1600x4780, 816 KB) Image created by User:(3ucky(3all using Borland Delphi 2006. ... Image File history File linksMetadata Download high-resolution version (1600x4780, 816 KB) Image created by User:(3ucky(3all using Borland Delphi 2006. ... It has been suggested that Line moiré be merged into this article or section. ...

Why black ink is used

The “black” generated by mixing Cyan, Magenta and Yellow primaries is unsatisfactory, and so four-color printing uses black ink in addition to the subtractive primaries. Common reasons for using black ink include:^[4] This article is about colors. ... Four-color printing creates an image using the subtractive colors cyan, yellow, magenta, and black. ...

• Text is typically printed in black and includes fine detail (such as serifs), so to reproduce text or other finely detailed outlines using three inks without slight blurring would require impractically accurate registration (i.e. all three images would need to be aligned extremely precisely).

• A combination of 100% cyan, magenta, and yellow inks soaks the paper with ink, making it slower to dry, and sometimes impractically so.

• A combination of 100% cyan, magenta, and yellow inks often results in a muddy dark brown color that does not quite appear black. Adding black ink absorbs more light, and yields much “blacker” blacks.

• Using black ink is less expensive than using the corresponding amounts of colored inks.

When a very dark area is desirable, a colored or gray CMY “bedding” is applied first, then a full black layer is applied on top, making a rich, deep black; this is called rich black.^[5] A black made with just CMY inks is sometimes called a composite black. In typography, serifs are non-structural details on the ends of some of the strokes that make up letters and symbols. ... Registration is a term used in the printing and desktop publishing industry. ... Rich black is a term used in printing to refer to a mixture containing all four of the cyan, magenta, yellow and black (CMYK) colors. ...

The amount of black to use to replace amounts of the other ink is variable, and the choice depends on the technology, paper and ink in use. Processes called under color removal, under color addition, and gray component replacement are used to decide on the final mix; different CMYK recipes will be used depending on the printing task. In four-color printing (or more) under color removal (UCR) is the process of eliminating amounts of yellow, magenta, and cyan that would have added to a dark neutral (black) and replacing them with black ink during the color separation process. ... In under color addition (UCA) the same results as under color removal can be obtained, but from a different starting position. ... Within the CMY color space, any hue angle can be achieved by combining two of the three primaries. ...

The same image, this time represented by the CMYK model. It is evident that significantly less color ink would be necessary to print this image when key is used.

Image File history File links Download high-resolution version (1600x4780, 669 KB) Image created by User:(3ucky(3all using Borland Delphi 2006. ... Image File history File links Download high-resolution version (1600x4780, 669 KB) Image created by User:(3ucky(3all using Borland Delphi 2006. ...

Other printer color models

CMYK or process color printing is contrasted with spot color printing, in which specific colored inks are used to produce the colors appearing on paper. Some printing presses are capable of printing with both four-color process inks and additional spot color inks at the same time. High-quality printed materials, such as marketing brochures and books, may include photographs requiring process-color printing, other graphic effects requiring spot colors (such as metallic inks), and finishes such as varnish, which enhances the glossy appearance of the printed piece. Printing technicians around the world use the term spot color to mean any color generated by a non-process color ink; such as metallic, fluorescent, spot varnish, or custom hand-mixed inks. ...

CMYK process printers often have a relatively small color gamut. Processes such as Pantone's proprietary six-color (CMYKOG) Hexachrome can considerably expand the gamut. Additionally, light, saturated colors often cannot be created with CMYK, and light colors in general can 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.^[6] In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... For the record label, see Pantone Music. ... Hexachrome is Pantones six-color printing process. ... CcMmYK is a six color printing process used in some inkjet printers optimized for photo printing. ... Ink jet printers are the most common type of computer printer; and industry and commerce also use them extensively for special-purpose applications. ...

Comparison with RGB

Comparisons between RGB displays and CMYK prints can be difficult, since the color reproduction technologies and properties are so different. A laser or ink-jet printer prints in dots per inch (dpi) which is very different from a computer screen, which displays graphics in pixels per inch (ppi). A computer screen mixes shades of red, green, and blue to create color pictures. A CMYK printer must compete with the many shades of RGB with only one shade of each of cyan, magenta and yellow, which it will mix using dithering, halftoning or some other optical technique; this dithering produces a lower level of detail than the printer's dpi suggests. Dots per inch (DPI) is a measure of printing resolution, in particular the number of individual dots of ink a printer or toner can produce within a linear one-inch (2. ... The square shown above is 200 pixels by 200 pixels. ... This article or section should be merged with Dither An illustration of dithering. ... Left: Halftone dots. ...

Conversion

Since RGB and CMYK spaces are both device-dependent spaces, there is no simple or general conversion formula that converts between them. Conversions are generally done through color management systems, using color profiles that describe the spaces being converted. Nevertheless, the conversions can not be exact, since these spaces have very different gamuts. This article does not cite any references or sources. ... It has been suggested that Color Matching Method be merged into this article or section. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ...

The problem of computing a colorimetric estimate of the color that results from printing various combinations of ink has been addressed by many scientists.^[7] A general method that has emerged for the case of halftone printing is to treat each tiny overlap of color dots as one of 8 (combinations of CMY) or of 16 (combinations of CMYK) colors, which in this context are known as Neugebauer primaries. The resultant color would be an area-weighted colorimetric combination of these primary colors, except that the Yule–Nielsen effect ("dot gain") of scattered light between and within the areas complicates the physics and the analysis; empirical formulas for such analysis have been developed, in terms of detailed dye combination absorption spectra and empirical parameters.^[7] Hans E. J. Neugebauer was a German-born physicist and imaging scientist who later lived in the United States and Canada. ... A phenomenon in printing and graphic arts whereby printed dots are perceived and actually printed bigger as intended. ...

References

is the 300th day of the year (301st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

See also

• Hexachrome
• Spot color
• CcMmYK color model
• Grey component replacement
• Under color removal
• Under color addition
• Four color printing
• Rich black

Hexachrome is Pantones six-color printing process. ... Printing technicians around the world use the term spot color to mean any color generated by a non-process color ink; such as metallic, fluorescent, spot varnish, or custom hand-mixed inks. ... CcMmYK is a six color printing process used in some inkjet printers optimized for photo printing. ... In grey component replacement (GCR), contrary to under color removal the CMY values that add to grey all along the tone scale can be replaced with up to the highlights with black ink. ... In four-color printing (or more) under color removal (UCR) is the process of eliminating amounts of yellow, magenta, and cyan that would have added to a dark neutral (black) and replacing them with black ink during the color separation process. ... In under color addition (UCA) the same results as under color removal can be obtained, but from a different starting position. ... Four-color printing creates an image using the subtractive colors cyan, yellow, magenta, and black. ... Rich black is a term used in printing to refer to a mixture containing all four of the cyan, magenta, yellow and black (CMYK) colors. ...

External links

• Color conversion (RGB / CMYK / HSV / YUV / ...) -- online conversion between color models
• XCmyk - CMYK to RGB Calculator with source code
• Color Space Fundamentals -- animated illustration of RGB vs. CMYK