Rich black
Encyclopedia
Rich black, in printing
, is an ink
mixture of solid black
over one or more of the other CMYK
colors, resulting in a darker tone than black ink alone generates in a printing process.
A typical rich black mixture might be 100% black, 50% of each of the other three inks. Other percentages are used to achieve specific results, for example 100% black with 70% cyan
, 35% magenta
, and 40% yellow
is used to achieve "cool" black. "Warm Black" is 100%K 60%M 60%Y and 35%C. The colored ink under the black ink makes a "richer" result: the additional inks absorb more light, resulting in a closer approximation of true black. While in theory an even richer black can be made by using 100% of each of the four inks, in practice the amount of non-black ink added is limited by the wetness that the paper
and printing process can handle. Wetness is not a problem with laser printer
s, however, and registration black
(or "400% black") produces very striking results in laser prints. Interesting effects can also be achieved with a laser printer by combining 100% black and 100% of cyan, magenta, or yellow.
Rich black is often regarded as a color that is "blacker than black". While this is nonsense from the point of view of color theory
, the difference can often be seen in the printed piece. The difference can also be apparent in backlit (also known as "translite") pieces, where rich black more thoroughly blocks the light from coming through.
The use of rich black has to be based on a full understanding of the printing conditions, including the inks, printing press
and especially the paper. If too much ink is used on poor quality paper such as newsprint
, this may cause the paper to literally fall apart. In addition, excessive amounts of ink may not have a chance to fully dry before the printed result comes into contact with other pages. The additional ink used to create rich black also results in higher printing costs.
Care must be taken when using electronic design programs; for example, when managing a CMYK document in Adobe Photoshop
, "black" may or may not equal 100%K depending on the CMYK profile specified in the image's settings, and Photoshop will represent the various tones using RGB
values close to black; whereas in an RGB document, "black" always equals RGB value (0,0,0).
Another reason to use rich black for small areas of black is to avoid trapping
issues. Rich black is often used for text printed over a picture or colored background, because otherwise any slight mis-registration between printing plates would produce a white or colored halo around the text, making it much harder to read.
In some cases the process of preparing a work to print may include conversions to CMYK from RGB or other color spaces. The amount of black mixed with C,M,Y inks can be expressed as a process of under color removal
or under color addition
, though increasingly the entire conversion process is done using an ICC profile
which expresses both the conversion and the under color handling.
Printing
Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
, is an ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
mixture of solid black
Black
Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light...
over one or more of the other CMYK
CMYK color model
The CMYK color model is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key...
colors, resulting in a darker tone than black ink alone generates in a printing process.
A typical rich black mixture might be 100% black, 50% of each of the other three inks. Other percentages are used to achieve specific results, for example 100% black with 70% cyan
Cyan
Cyan from , transliterated: kýanos, meaning "dark blue substance") may be used as the name of any of a number of colors in the blue/green range of the spectrum. In reference to the visible spectrum cyan is used to refer to the color obtained by mixing equal amounts of green and blue light or the...
, 35% magenta
Magenta
Magenta is a color evoked by light stronger in blue and red wavelengths than in yellowish-green wavelengths . In light experiments, magenta can be produced by removing the lime-green wavelengths from white light...
, and 40% yellow
Yellow
Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...
is used to achieve "cool" black. "Warm Black" is 100%K 60%M 60%Y and 35%C. The colored ink under the black ink makes a "richer" result: the additional inks absorb more light, resulting in a closer approximation of true black. While in theory an even richer black can be made by using 100% of each of the four inks, in practice the amount of non-black ink added is limited by the wetness that the paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
and printing process can handle. Wetness is not a problem with laser printer
Laser printer
A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and multifunction printers , laser printers employ a xerographic printing process, but differ from analog photocopiers in that the image is produced...
s, however, and registration black
Registration black
In CMYK printing, registration black refers to 100% coverage in each of the four process colors: cyan , magenta , yellow , and black...
(or "400% black") produces very striking results in laser prints. Interesting effects can also be achieved with a laser printer by combining 100% black and 100% of cyan, magenta, or yellow.
Rich black is often regarded as a color that is "blacker than black". While this is nonsense from the point of view of color theory
Color theory
In the visual arts, color theory is a body of practical guidance to color mixing and the visual impacts of specific color combinations. Although color theory principles first appeared in the writings of Leone Battista Alberti and the notebooks of Leonardo da Vinci , a tradition of "colory theory"...
, the difference can often be seen in the printed piece. The difference can also be apparent in backlit (also known as "translite") pieces, where rich black more thoroughly blocks the light from coming through.
The use of rich black has to be based on a full understanding of the printing conditions, including the inks, printing press
Printing press
A printing press is a device for applying pressure to an inked surface resting upon a print medium , thereby transferring the ink...
and especially the paper. If too much ink is used on poor quality paper such as newsprint
Newsprint
Newsprint is a low-cost, non-archival paper most commonly used to print newspapers, and other publications and advertising material. It usually has an off-white cast and distinctive feel. It is designed for use in printing presses that employ a long web of paper rather than individual sheets of...
, this may cause the paper to literally fall apart. In addition, excessive amounts of ink may not have a chance to fully dry before the printed result comes into contact with other pages. The additional ink used to create rich black also results in higher printing costs.
Care must be taken when using electronic design programs; for example, when managing a CMYK document in Adobe Photoshop
Adobe Photoshop
Adobe Photoshop is a graphics editing program developed and published by Adobe Systems Incorporated.Adobe's 2003 "Creative Suite" rebranding led to Adobe Photoshop 8's renaming to Adobe Photoshop CS. Thus, Adobe Photoshop CS5 is the 12th major release of Adobe Photoshop...
, "black" may or may not equal 100%K depending on the CMYK profile specified in the image's settings, and Photoshop will represent the various tones using RGB
RGB color model
The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors...
values close to black; whereas in an RGB document, "black" always equals RGB value (0,0,0).
Another reason to use rich black for small areas of black is to avoid trapping
Spreading and choking
Trapping is a term most commonly used in the prepress industry to describe the compensation for misregistration between printing units on a multicolor press. This misregistration causes unsightly gaps or white-space on the final printed work...
issues. Rich black is often used for text printed over a picture or colored background, because otherwise any slight mis-registration between printing plates would produce a white or colored halo around the text, making it much harder to read.
In some cases the process of preparing a work to print may include conversions to CMYK from RGB or other color spaces. The amount of black mixed with C,M,Y inks can be expressed as a process of under color removal
Under color removal
Ideally, CMY without black should complete the printing process; however, sufficiently pure CMY ink has not been developed, and for this reason, black ink is used to add details and darkness in shadowed areas...
or under color addition
Under color addition
In four-color printing , under color addition is a technique for darkening areas of the printed image by adding colored inks...
, though increasingly the entire conversion process is done using an ICC profile
ICC profile
In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium...
which expresses both the conversion and the under color handling.