Are you up to date on the latest color-related standards and process guidelines, what they mean for your business? These frequently asked questions (and answers!) will help ensure you have implemented the latest best practices, especially as they relate to optical brightening agents (OBAs) and the effect they have on color measurement and management. We’ve included simple descriptions as well as more technical information you might need as you assess the state of your color measurement and management processes.
Why should I care?
Accurate, predictable and repeatable color requires a consistent process, with process control over the complete workflow, including prepress, proofs, plates and the pressroom. Process control brings print processes into compliance with industry standards and guidelines and helps companies maintain consistency throughout a print run and from job to job. This means operations more consistently meet customer expectations, reduce waste and rework, and operate more competitively and profitably. It requires the use of color measurement instruments, control bars, clearly specified tolerances that fall within International Standards Organization (ISO) standards, and the implementation of standard operating procedures (SOPs) across the organization that everyone complies with.
What are the ISO standards that relate to graphics technology?
There are many! These are the most important:
What is the difference between standards and guidelines?
The International Standards Organization (ISO) develops the standards which specify the intent and guidelines. Then regional organizations establish additional implementation guidelines and documentation that describes how to achieve their specification. For example, for ISO 12647, which focuses on conventional printing processes, regional guidelines include PSO, FOGRA, GRACoL, SWOP and more.
CGATS, the Committee for Graphic Arts Technologies Standards, is another accredited standards body, responsible for developing standards for the U.S. printing and publishing industries.
DIN's Standards Committee for Graphic Technology (NDR) is responsible for developing national standards for the printing industry in Germany, including printing technology and multi-media services.
GRACoL (General Recommendations for Commercial Offset Lithography), developed by IDEAlliance, is now based on ISO/PAS 15339-2:2013 and CGATS 21-2. G7 near neutral calibration is the process control methodology used to comply with the GRACoL guidelines and is widely used in North America. IDEAlliance provides characterization data and ICC profiles for GRACoL.
IDEAlliance also maintains SWOP (Specification for Web Offset Publication) primarily used by magazine publishers, prepress associates advertising agencies and web offset printers. It is based on the G7 process control methodology and provides characterization data and ICC profiles for paper types 3 and 5.
Fogra is a German research institute for the graphic arts that is actively involved in maintaining several color management specifications. Data produced using Fogra test charts can be used to create ICC profiles for a variety of presses. Fogra and Bundesverband Druck & Medien (BVDM) published PSO (Process Standard Offset) to describe standardized procedures for manufacturing printed products to achieve predictable color and is widely used in Europe. The organization also provides characterization data and profiles along with ECI (European Color Initiative) that represents printing based on PSO, with FOGRA51/52 being the most relevant here.
What are FOGRA51/52?
FOGRA51 and FOGRA52 include characterization data for ISO 12647-2:2013 based printing on matte/glossy coated and uncoated offset papers. The final ICC color profiles were developed in a cooperative effort by BVDM, ECI, Fogra and Ugra. These profiles are named PSOcoated_v3.icc (FOGRA51) and PSOuncoated_v3_FOGRA52.icc. Fogra offers a number of certification programs for print providers, proofing systems and proof providers.
These have been recently updated to include the M1 mode to account for optical brighteners in paper in compliance with new ISO standards.
What is G7?
G7 is both a definition of grayscale appearance and a calibration method for adjusting any CMYK imaging device to simulate the G7 grayscale definition. It was developed and is maintained by IDEAlliance, who offers a number of G7 certification programs.
G7 yields a visual match between different imaging systems using simple 1-dimensional curves, and enables shared appearance among different printing devices or specifications when additional color management is not available.
G7 is the basis for GRACoL on #1 paper, SWOP on #3 paper, SWOP on #5 paper and FIRST’s Flexo on white polyester substrate (TR007). G7 is defined in CGATS.15 and is the basis for the data sets in ISO/PAS 15339-2, which requires M1 measurements to account for optical brighteners in paper in compliance with other new ISO standards.
What is M1 and why it is important?
As part of ISO 13655-2009: Spectral Measurement and Colorimetric Computation for Graphic Arts Images, a new set of measurement standards, the “M” series of measurement illumination conditions, has been defined by ISO to standardize illumination conditions appropriate for different applications when substrates contain brightening agents. The new M series allows color management of OBA-enhanced substrates to be further refined to a very high degree.
The need for the M series is driven by the color changes seen in materials containing OBAs when viewed with different light sources. The effects of three different illumination conditions on the same paper with and without optical brighteners are significant. The amount of change between the three illuminants on papers with brightening agents would result in an unacceptable match in many workflows and to many clients in the Graphic Arts. In order to minimize this measurement variability, and to provide a way to communicate the illumination source used for measurement, a new notation of measurement illumination conditions was developed for inclusion in ISO 13655. It defines four distinct measurement illumination conditions, one of which is M1. The full range of M-series measurement illumination conditions includes:
The M1 measurement mode or condition helps to identify and to reduce variations in measurement results between instruments due to fluorescence, either by optical brighteners in paper or fluorescence of the imaging colorants or proofing colorants. M1 (Part One) specifies that the spectral power distribution of the light source used to measure the specimen should match CIE Illuminant D50. M1 also defines a second (Part Two) method for achieving M1 compliance that is only valid for measuring optically brightened papers but not for measuring inks or toners that fluoresce. This is due to the historical complexity of delivering true D50 illumination in handheld instruments. This second definition only requires that a compensation method is used with a controlled adjustment of the amount of UV component (spectral region below 400 nm) used to measure. This is to provide correlation to the D50 illumination conditions as defined in ISO 3664:2009 viewing standard. This second method must be tied to a viewing condition compliant with ISO 3664:2009, so caution in using it must be exercised, and testing for agreement is advised.
How can the M1 condition be used with X-Rite eXact?
X-Rite eXact uses the M1 condition for a single measurement, where the user can configure eXact to get measurements based on customer specification. In addition to the ability to download existing PSO (Process Standard Offset), Fogra or G7 jobs with presets for reaching target ISO values much faster, eXact is a powerful manual tool. Check here to see specifications for white and black backing for all 8 paper types; and TVI (dot gain) definition of 25, 50, 75% and 40, 80%. Also included are job templates for PSO, G7 and GRACoL that can be loaded into the eXact for ease of use.
This is also true of the Pantone Color Guides. All Pantone Libraries have all 4 measurement conditions – M0, M1, M2 and M3 for different requests and workflow setup. Customers can use any of them, but it is important to keep same conditions across a digital workflow.
X-Rite eXact is the only handheld device on the market that can measure a true M1 Part One (not a simulated M1 Part Two, but rather matching D50 (Daylight) in the entire visible spectrum and conforming to the UV range metamerism index specified in ISO 3664) AND capture M0, M2 and M3 simultaneously in less than one second, for both spot and scan readings. With a simple toggle, the instrument can be switched between M1 and M0/2/3 measurement modes so that measurements can be quickly and easily taken and stored. With the eXact touch screen interface, users can easily view M0, M2 and M3 measurements as required. It supports all measurement modes according to ISO 13655:2009 (M0, M1, M2, and M3).
Correct practical implementation will result in the best PSO/Pantone performance.
Most International Certifications such as PSO and the Pantone Certified Printer Program require measurement conditions in compliance with the existing ISO 13655-2009 standard. In the past, PSO was based on M0 conditions; now it is M1 compliant (according to requirements in ISO 12647-2). Pantone Certification is independent of any measurement conditions, but one of the most important components is consistent results. Once a Job or reference is established with M1 or any other conditions, all parts of the workflow must utilize it. This is also important for brand owners who want to produce digital references on their own. Once the color is captured, the values should not change unless the color transformation is properly described in SOPs (Standard Operation Procedures).