Specifications for Web Offset Publications

Last updated January 19, 2022

Specifications for Web Offset Publications, invariably abbreviated to SWOP, is an organization and the name of a set of specifications that it produces, with the aim of improving the consistency and quality of professionally printed material in the United States, and of certain other products, programs and endorsements related to their work. Among other things, the organization specifies SWOP inks used in CMYK printing, colors of SWOP proofs , other physical qualities pertaining to printing. The organization publishes its own specification and ICC profile and runs a certification program.

Similar to SWOP is GRACoL originally by Graphics Communication Association, which defines a similar set of specifications for sheetfed printing. By 2005, both specifications are merged into a think tank called IDEAlliance with their own working groups. By 2006, both are unified under the framework of CGATS 21.^[1]

History

Early work of specifying U.S. print color started in 1975 and resulted in a set of best practices, the precursor to SWOP. By the late 1980s, digitization of printing lead the SWOP committee to seek cooperation with CGATS, the ANSI Committee for Graphic Arts Technical Standards. The result was CGATS TR001, an ANSI technical report that specifies the colorimetric measurements of standard SWOP ink and media. In 2005, SWOP was merged into IDEAlliance.^[1]

GRACoL was founded in 1996 with the goal of specifying sheetfed printing in a similar way to SWOP. Annual specifications were published from 1997-2002. In 2006, SWOP and GRACol (coated CPRC6, uncoated CPRC3) was redefined in the G7 calibration method, which is also used in ISO/PAS 15339 or CGATS 21 defining the Characterized Reference Print Conditions (CPRCs). The standard defines SWOP as CPRC5, coated GRACol as CPRC6, and uncoated GRACol as CPRC3.^[1]

GRACoL-SWOP 2006 uses the ISO 12647-2:2004 paper. The 2013 revision uses a slightly bluer paper as the old paper is considered legacy by the authors. GRACoL/CPRC6 aligns mostly with ISO 12647-2 PC1, although the TVI for "K" is slightly different due to G7 calibration.^[1]

Scope

The SWOP specification covers many areas related to print production, complementing, extending and limiting those in other industry standards. The specification includes (but is not limited to) the following.

A specification for the colors of the cyan, magenta, yellow and black ("key") inks used in CMYK printing. Inks conforming to the specification can be called SWOP inks. The specifications make reference to, but are not identical to, the ISO standard ISO 2846-1:2006.
A specification for the colors of proofs produced by various technologies, so they are accurate representation of the SWOP inks eventually used to print. (See SWOP Certification Program below). Proofs made from systems that meet these specifications may be called SWOP Proofs.
Specifications for expected dot gain (caused by ink dots enlarging over absorbent papers), also known as tone value increase (TVI). G7-based versions use an alternative definition (see CGATS TR015).^[1]
Requirements for producing halftones and color separation
Design constraints, such as the minimum size of type which is to printed reversed or knocked out of a background, to keep legibility.
Production constraints, such as a limit of 300% on the total mixture of inks (taking a mixture of 100% each of cyan, magenta, yellow and black as being 400%).

SWOP also endorse, produce or specify some other things.

ICC profiles for color management, based on the standard called TR001, an ANSI technical report whose full title is “CGATS TR001-1995 Graphic Technology-Color Characterization Data for Type 1 Printing.” A number of profiles using TR001 are made with SWOP in the title, such as the profile USWebCoated (SWOP), which is widely available because it is included with many Adobe applications. TR001 profiles are not universal, because they were generated and tested with specific inks, papers, and printing technologies.
The SWOP booklet gives the specifications mentioned above, often in reference to other industry specifications (ISO and other).
A SWOP Certification Program for proofing (not press) printing systems. This is used by manufacturers, rather than purchasers, of systems.

Related Research Articles

Cyan is the color between green and blue on the visible spectrum of light. It is evoked by light with a predominant wavelength between 490 and 520 nm, between the wavelengths of green and blue.

The CMYK color model is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key (black).

Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word processing, optical character recognition, image manipulation, desktop publishing, and page-layout applications. The format was created by the Aldus Corporation for use in desktop publishing. It published the latest version 6.0 in 1992, subsequently updated with an Adobe Systems copyright after the latter acquired Aldus in 1994. Several Aldus or Adobe technical notes have been published with minor extensions to the format, and several specifications have been based on TIFF 6.0, including TIFF/EP, TIFF/IT, TIFF-F and TIFF-FX.

In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media.

Giclée is a neologism coined in 1991 by printmaker Jack Duganne for fine art digital prints made on inkjet printers. The name was originally applied to fine art prints created on a modified Iris printer in a process invented in the late 1980s. It has since been used loosely to mean any fine-art printing, usually archival, printed by inkjet. It is often used by artists, galleries, and print shops to suggest high quality printing, but is an unregulated word with no associated warranty of quality.

In printing, under color removal (UCR) is a process of eliminating overlapping yellow, magenta, and cyan that would have added to a dark neutral (black) and replacing them with black ink only, called a Full Black, during the color separation process. Under color removal is used in four-color printing. Black ink used to add details and darkness in shadowed areas is called a Skeletal Black.

In offset printing, a spot color or solid color is any color generated by an ink that is printed using a single run, whereas a process color is produced by printing a series of dots of different colors.

Color printing or colour printing is the reproduction of an image or text in color. Any natural scene or color photograph can be optically and physiologically dissected into three primary colors, red, green and blue, roughly equal amounts of which give rise to the perception of white, and different proportions of which give rise to the visual sensations of all other colors. The additive combination of any two primary colors in roughly equal proportion gives rise to the perception of a secondary color. For example, red and green yields yellow, red and blue yields magenta, and green and blue yield cyan. Only yellow is counter-intuitive. Yellow, cyan and magenta are merely the "basic" secondary colors: unequal mixtures of the primaries give rise to perception of many other colors all of which may be considered "tertiary."

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.

The HKS is a colour system which contains 120 spot colours and 3520 tones for coated and uncoated paper. HKS is an abbreviation of three German colour manufacturers: Hostmann-Steinberg Druckfarben, Kast + Ehinger Druckfarben, and H. Schmincke & Co. The association of those three companies have defined the colours of the HKS system since 1968.

CcMmYK, sometimes referred to as CMYKLcLm or CMYKcm, is a six-color printing process used in some inkjet printers optimized for photo printing. It complements the more common four color CMYK process, which stands for Cyan, Magenta, Yellow and Key (black), by adding light cyan and light magenta. Individually, light cyan is often abbreviated to Lc or c, and light magenta is represented as Lm or m.

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 (ICC). Profiles describe the color attributes of a particular device or viewing requirement by defining a mapping between the device source or target color space and a profile connection space (PCS). This PCS is either CIELAB (L*a*b*) or CIEXYZ. Mappings may be specified using tables, to which interpolation is applied, or through a series of parameters for transformations.

PDF/X is a subset of the PDF ISO standard. The purpose of PDF/X is to facilitate graphics exchange, and it therefore has a series of printing-related requirements which do not apply to standard PDF files. For example, in PDF/X-1a all fonts need to be embedded and all images need to be CMYK or spot colors. PDF/X-3 accepts calibrated RGB and CIELAB colors, while retaining most of the other restrictions of PDF/X-1a.

IT8 is a set of American National Standards Institute (ANSI) standards for color communications and control specifications. Formerly governed by the IT8 Committee, IT8 activities were merged with those of the Committee for Graphics Arts Technologies Standards in 1994.

A variety of tests are used to determine ink and paper and paperboard quality, and to measure their interactions. They are necessary to balance print quality, cost, and wear on the press. Some of the important paper and ink tests are listed here:

A contract proof usually serves as an agreement between customer and printer and as a color reference guide for adjusting the press before the final press run. Most contract proofs are a prepress proof.

Monitor proofing or soft-proofing is a step in the prepress printing process. It uses specialized computer software and hardware to check the accuracy of text and images used for printed products. Monitor proofing differs from conventional forms of “hard-copy” or ink-on-paper color proofing in its use of a calibrated display(s) as the output device.

The G7 Method is a printing procedure used for visually accurate color reproduction by putting emphasis on matching grayscale colorimetric measurements between processes. G7 stands for grayscale plus seven colors: the subtractive colors typically used in printing and the additive colors. The method is used in many applications of printing such as offset lithography, flexography, and gravure since it uses a one-dimensional neutral print density curve (NPDC) to match neutral tonality between two G7 calibrated printing systems. The G7 method is not a completely accurate color management system nor is it officially standardized by the International Color Consortium (ICC).

Media Standard Print is a publication of the Bundesverband Druck und Medien, available on its website. The standard contains instructions on how to produce data and proofs that are to be sent to a printer. It is based on ProcessStandard Offset and therefore on the ISO Standards ISO 12647 and ISO 15930. As such, it serves as the foundation for smooth cooperation between customer, prepress service provider and printer during media production, covering data formats, colour formats, printing conditions, workflows, means of proofing, standards, black composition and much more.

The European Color Initiative (ECI) is an expert group that is concerned with media-neutral reproduction of color data in digital publication systems. It was formed in June 1996 by German publishers Bauer, Burda, Gruner + Jahr and Springer in Hamburg.

References

1 2 3 4 5 "GRACoL & SWOP". Guide to Print Production (13 ed.). IDEAlliance. p. 14. Archived from the original on 2019-03-29. Retrieved 6 December 2019.

External links

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[printprod-swop-1] 1 2 3 4 5 "GRACoL & SWOP". Guide to Print Production (13 ed.). IDEAlliance. p. 14. Archived from the original on 2019-03-29. Retrieved 6 December 2019.

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