CMYK color model

{{Short description|Subtractive color model used in printing}} {{Redirect|CMYK|the extended play (EP) by James Blake|CMYK (EP){{!}}''CMYK'' (EP)}} {{Redirect|CMYB|the cMyb gene tree|MYB (gene)}}

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| image1 = CMYK Color Swatches.svg | width1 = 180 | alt1 = CMYK swatches | caption1 = Ink used in four-color printing: cyan, magenta, yellow, and black. | image2 = CMYK color model.svg | width2 = 180 | alt2 = CMYK model diagram | caption2 = Pairwise combinations of cyan, magenta, and yellow inks produce red, green, and blue. All three combined produce an imperfect black. }}

{{Multiple image | direction = vertical | image1 = CMYK closeup.jpg | image2 = CMYK under a microscope.jpg | caption2 = A color perceived as cerulean ({{Color sample|#489490}}) is a blend of cyan, magenta, yellow, and black inks, as observed under magnification. }}

The '''CMYK color model''' is a subtractive color model used in color printing as well as describing the printing process. The abbreviation ''CMYK'' refers to the four color components used in printing: cyan, magenta, yellow, and black (the ''key'' plate).<ref name="MixamCMYK">Mixam Print Support: CMYK colour charts and values. [https://mixam.com/support/cmykchart]</ref>

In subtractive models, inks reduce the amount of light reflected from a white or light background. White is the color of the substrate, and black results from the combination of inks. This contrasts with additive color models (e.g., RGB color model), where colors are produced by emitting light, white results from combining all primary colors, and black represents the absence of light. The addition of black ink reduces ink consumption and produces more consistent dark tones compared to using cyan, magenta, and yellow alone.

The CMYK printing process was first implemented in the 1890s for color newspaper illustrations and comic strips.

== Halftoning == {{Main|Halftone}} thumb|Diagram showing color halftoning with CMYK separations. The combined halftone pattern appears as a uniform color to the human eye at sufficient viewing distance.

''Halftoning'' (or ''screening'') allows a printer to produce continuous tones by varying the size and spacing of small ink dots. This creates the perception of intermediate colors between the primary inks. For example, 20% coverage of magenta ink produces a pink tone rather than full magenta.<ref>{{cite book|url=https://books.google.com/books?id=nRoMo3V5AEwC&pg=PA1|title=Digital Color Halftoning|page=1|last=Kang|first=Henry R.|publisher=SPIE Press|year=1999|isbn=0-8194-3318-7}}</ref><ref>{{Cite book|title=Color Theory For Dummies|url=https://www.google.com/books/edition/Color_Theory_For_Dummies/bXR-EAAAQBAJ|publisher=John Wiley & Sons|date=2022-07-29|isbn=978-1-119-89228-1|language=en|first=Eric|last=Hibit|pages=192}}</ref>

Without halftoning, CMYK inks would only produce eight colors: the three primaries (cyan, magenta, yellow), the three secondaries (red, green, blue), white, and black.

== Comparison to CMY == thumb {{Multiple image|width=197|image1=CMY separation – no black.jpg|image2=CMYK separation – maximum black.jpg|footer=Comparison of printing separations: CMY (left) vs CMYK (right).}} thumb|CMYK ink on offset-printed paper

CMYK is an extension of the CMY model, which omits black ink. Black ink is added in four-color printing for several practical reasons:<ref>{{cite book |author=Roger Pring |url=https://archive.org/details/wwwcolor00prin |title=WWW.Color |publisher=Watson–Guptill |year=2000 |isbn=0-8230-5857-3 |page=178}}</ref>

* The "key" (K) plate provides outlines and text with higher precision than using three inks alone.<ref>{{cite web|url=https://gizmodo.com/the-difference-between-rgb-and-cmyk-explained-1777830600|title=The Difference Between RGB and CMYK, Explained|last=Menegus|first=Bryan|website=Gizmodo|date=May 20, 2016|access-date=October 4, 2020}}</ref> * Using black ink reduces ink consumption and drying time, preventing paper distortion or tearing. * Combining 100% cyan, magenta, and yellow produces a dark but imperfect black; black ink produces more consistent dark tones. * Black ink is more cost-effective than combining three colored inks.

A dark area printed with CMY and then overlaid with black is referred to as ''rich black''.<ref>{{cite book |title=The Guild Handbook of Scientific Illustration |author=R. S. Hodges|url=https://books.google.com/books?id=YWaOBSjevD0C&pg=PA242|page=242|year=2003|publisher=John Wiley and Sons |isbn=0-471-36011-2 }}</ref>

Techniques such as under color removal, under color addition, and gray component replacement determine the amount of black ink relative to other inks.<ref>{{cite book|url=https://books.google.com/books?id=VrdqBRgSKasC&pg=PA87|page=87|title=Handbook of Print Media: Technologies and Production Methods|editor-last=Kipphan|editor-first=Helmut|publisher=Springer|year=2001|isbn=3-540-67326-1}}</ref>

== Other printer color models == CMYK contrasts with spot color printing, where specific inks produce fixed colors. Some presses can combine process and spot colors. High-quality printed materials often require full-color process printing, sometimes augmented with spot colors or metallic inks.<ref name="Collins2020">{{cite book |last1=Collins |first1=Wayne |last2=Bahr |first2=Alex |last3=Kuo |first3=Gwen |title=Graphic Design and Print Production Fundamentals |date=2020 |publisher=Graphic Communications Open Press |url=https://opentextbc.ca/graphicdesign/ |archive-url=https://web.archive.org/web/20251103135119/https://opentextbc.ca/graphicdesign/ |archive-date=November 3, 2025 |url-status=live |access-date=December 23, 2025 |quote=Process colors are typically used when a design requires full-color printing or when it includes complex images like photographs.}}</ref><ref>{{cite web |last=Davies |first=Helen |date=August 3, 2020 |title=Top 8 Large Format Printing Tips To Achieve High-End Projects |url=https://www.frontsigns.com/blog/top-large-format-printing-tips-to-achieve-the-highest-quality/ |url-status=live |archive-url=https://web.archive.org/web/20200929015633/https://www.frontsigns.com/blog/top-large-format-printing-tips-to-achieve-the-highest-quality/ |archive-date=September 29, 2020 |access-date=October 4, 2020 |website=Front Signs}}</ref>

Extended gamut systems (e.g., CMYKOG Hexachrome) increase the range of reproducible colors beyond standard CMYK.<ref>{{cite journal|url=https://www.spiedigitallibrary.org/conference-proceedings-of-spie/5008/1/3D-color-separation-maximizing-the-printer-gamut/10.1117/12.472012.short?SSO=1|title=3-D Color Separation Maximizing the Printer Gamut|last=Zeng|first=Huanzhao|journal=Proceedings of SPIE|volume=5008|year=2003|page=260|doi=10.1117/12.472012}}</ref>

== Comparison with RGB displays == thumb|Comparison of RGB and CMYK gamuts on the CIE 1931 ''xy'' chromaticity diagram

RGB displays emit light and produce additive colors, while CMYK inks absorb light and produce subtractive colors.<ref name="Stone2003">{{cite book |last=Stone |first=Maureen C. |title=A Field Guide to Digital Color |date=2003 |publisher=A K Peters/CRC Press |isbn=978-1568811611 |page=11}}</ref> Each model has a distinct color gamut; colors visible on one may not be reproducible on the other.<ref name="Wyszecki2000">{{cite book |last1=Wyszecki |first1=Günther |last2=Stiles |first2=W. S. |title=Color Science: Concepts and Methods, Quantitative Data and Formulae |date=2000 |publisher=Wiley-Interscience |isbn=978-0471399186 |edition=2nd |page=174}}</ref>

=== Spectrum of printed paper === The CMYK model codes for absorption of light. Cyan absorbs red, magenta absorbs green, and yellow absorbs blue. Black ideally absorbs all wavelengths.<ref>{{cite web|url=https://www.physics.wisc.edu/ingersollmuseum/exhibits/opticscolor/subcolormix/|title=Subtractive Color Mixing|publisher=L. R. Ingersoll Physics Museum|access-date=October 4, 2020}}</ref>

thumb|upright=2.5|Spectrum of printed wavelengths on paper. Readings from several flower petals are shown for comparison.

== Conversion == RGB and CMYK are device-dependent; no universal formula converts between them. Color management systems using ICC profiles are required to map between devices accurately. Conversion depends on device gamuts, rendering intents, and factors such as dot gain and Neugebauer primaries.<ref name=Sharma>{{cite book | title = Digital Color Imaging Handbook | author = Gaurav Sharma | year = 2003 | publisher = CRC Press | isbn = 0-8493-0900-X | url = https://books.google.com/books?id=AkByHKRGTsQC&pg=PA68|page=68}}</ref>

Predefined printing standards, such as Specifications for Web Offset Publications, include ICC profiles for software and operating systems.<ref>{{cite web |title=KB933845 How to obtain and install the Microsoft Standard CMYK Profile (RSWOP.icm) in Windows Vista |url=https://www.betaarchive.com/wiki/index.php/Microsoft_KB_Archive/933845 |website=Beta Archive |access-date=1 September 2023 |date=March 15, 2007}}</ref>

<gallery widths=255 heights=400 class="center" > File:NIEdot367.jpg|Early three-color process (1902) File:NIEdot367-modern.jpg|Approximation using CMY colors </gallery>

== References == {{reflist}}

== External links == {{Commons category|CMYK}} * [http://www.codeproject.com/KB/applications/xcmyk.aspx XCmyk] – Windows software for CMYK-RGB conversion * [https://www.edusters.com/tool/rgb-to-cmyk-color-converter-online.php RGB to CMYK converter] – Online conversion tool * [https://web.archive.org/web/20110716053923/http://dx.sheridan.com/advisor/cmyk_color.html Color Space Fundamentals] – Animated illustration of RGB vs CMYK * [https://www.color.org/registry/index.xalter ICC profile registry] – Standard CMYK profiles, paper types, and separation limits

Category:Color space Category:Printing Category:Printing terminology