Pathways to ISO compliance
In this article Mark Stegman, NSW TAFE lecturer explains the processes of becoming ISO 12647-2 compliant.
Demystifying the processTo the uninitiated coming to terms with ISO standards can be complex and mystifying. Many a frown has been born when confronted with a technical standards document or even the summary of its contents.
The terminology is often too technical for the layman and the language obscure. This is one thing you just have to get used to as these documents often serve as a reference in any dispute on what is, and is not, possible between parties in a legally binding commercial contract. Terminology has to be precise and all possible scenarios have to be addressed. So it isn't surprising that some of these documents can be a bit hard to understand.
One of the first things to remember is that the standards do not exist in isolation. They are interdependent.
Each standard is defined in technical terms: parameters and tolerances which can be measured. The method and circumstances for taking these measurements are also described. In doing so, definitions and descriptions from associated standards come into play. For example, one of the factors stipulated in the standard ISO 12647-2 is that the inks used for the printing process must comply with the specifications in the relevant part of ISO 2846. This standard defines the colour and transparency of printing inks and how it is measured. These properties: colour and transparency, are described by measurements recorded with appropriate instrumentation. In turn, the performance of such instruments (spectrophotometers, densitometers and colorimeters) is also defined within another standard.
This type of interdependence is necessary to ensure that the aim of setting a realistic yet achievable standard can not be easily circumvented by using, for example, one instrument rather than another, to do the measurements. In fact, variability of instruments is still a contentious topic within the realms of colour management and quality control but the overall achievement of objective scientific monitoring of production processes and their output has produced positive results and will only get better.
Once you've 'cracked the code' and come to terms with the contents of ISO standards the next stage is implementation.
In this section we will outline the connection between ISO standards and their implementation. In short, when you aim to meet a standard you are aiming at compliance. That is, the work you produce will fall inside the parameters and tolerances defined in the standard.
As we have already explained, or at least implied, this work will have to be monitored, using scientific instruments and manageable methods of quality control. Printed sheets and proofs alike will have to have quality control devices (control strips) that are measurable. The measurements will have to fall within the tolerances specified within the standard. "Is that new?" I hear you say. “No”, except for the measurements we take and tolerances we allow.
Instead of monitoring your printed output by densities alone we now record measurements in the values of device independent colour spaces: L*a*b* or XYZ. These values describe colour in a way that does not relate to any specific device. The measurement is removed from the realm of device specific numbers such as 30% C, 60%Y and 5%M.
As a result you will NOT find colour tolerances inside an ISO standard described in terms of their CMYK values. They are described in the more 'absolute' values of the Lab colour model.This means that, in theory, you could use your own separation set-up (RGB to CMYK conversion), your own specific ink sets (as long as they conform to the specifications of the ink standard), substrate, and printing press and still achieve a result that is compliant with the ISO print standard. Just how feasible this is, is another question! As long as you used the same combination of ink, paper and press to achieve the same result there is no reason that this could not be done consistently given proper quality control.
However, the distinction has to be made between what is in the standard and what is not.
Standards DO NOT necessarily prescribe how to achieve compliance: yet you need to know how to get ‘there’. The aim of this article is to assist in explaining your options or “pathways to compliance”.
Standards simply describe the parameters by which compliance is measured. In the case of colour reproduction it is defined in Lab values. In other words, it is possible to achieve the same or similar result with the standard inks using different relative values of CMYK. After all, this is what GCR and UCR were originally designed for: saving ink by using different relative CMYK values to achieve the same visual result. These days the visual result is measured in L*a*b* so this could now read "the same colorimetric result".
These specific sets of CMYK values are what go together with the L*a*b* values to constitute an ICC press profile. So, different profiles can achieve ISO compliance using the same printing conditions: ink, paper, press and process.
Who does all this monitoring, measuring and profiling?Reading all the available literature on ISO standards it is easy to think that all you have to do is what you have always done: implement basic quality control. That is correct. However, targeting a specific standard, or more precisely, the values and specifications within the standard, often requires monitoring of the whole workflow including proofing and prepress operations.
Users have to be literate in colour management terms and technologies and understanding the importance of maintaining consistent quality control throughout the print run. It means having an accurate understanding of what it takes to have your presses produce consistent, ISO compliant product. That means having consistent ink and paper supplies and running the press to consistent densities. It also means maintaining a production environment with standard viewing conditions and ISO compliant proofing. That is, identifying and controlling all of the variables in the production process. You, the printer, CAN do all this yourself OR you can go another path and engage someone to help you.
Isn't this a lot of work?“Yes”. However, the advantages in terms of productivity are great. Creating your own device specific profiles is probably the most time-consuming and expensive part. The rest of the compliance process with respect to quality control should be standard procedure: standard inks, consistent densities and viewing conditions. However, until recently, the printing industry has not been subjected to the same rigorous demands of other mass production industries.
What’s the alternative?The alternative to doing all the implementation yourself is that you could use a profile generated from 'characterisation' data from a press that was performing within the ISO specification and then get your press to behave in much the same way. Instead of making customised profiles of each press we turn the process ‘on its head’ and get the presses to target the profile.
Using a pre-determined profile such as ISOcoated_v2_300_eci.icc, ISOcoated_v2_eci.icc, the GRACol 7 specification (GRACoL2006_Coated1v2.icc), or some other third-party generated ISO based profile by-passes a lot of the work.
You could call these profiles “standardised” although it is not technically right as there are no profiles defined within the standard: only tolerances in L*a*b*. Subsequently, profiles of this type tend to include the name of the creator such as ISOcoated_v2_eci.icc (the profile created by the European Colour Initiative (www.eci.org). This profiles is based on the characterisation data produced by FOGRA: FOGRA_39L.txt. (This data, and profile, account for changes to the ink standard [ISO 2846-2:2007] which were responsible for the amendment to the ISO print standard: 12647-2:2004/Amd 1:2007).
In the case of FOGRA a specific workflow is prescribed: Process Standard Offset printing (PSO). This method describes the type of ink, paper and press - the printing conditions - required to achieve compliance using the profile they have generated. In order to qualify for their ‘certification’ they require you to submit to an audit process using press sheets and proofs as evidence. In doing so it is claimed they have saved you all the hard and expensive work. Instead of developing your own profile that complies with the standard, you use their resources and comply not only with the standard but also with their methods of achieving it. When you look at the amount of time and resources devoted to such an exercise this is a fairly solid claim.
Apart from FOGRA there are other research and development organisations that offer similar certification processes such as UGRA (www.ugra.ch) however, the UGRA certification still uses the FOGRA characterisation data and PSO method. GRACol (in the USA) has also developed their own approach to producing consistent print that conforms to the same standard: ISO 12647-2. Their methodology, G7, is described as a 'calibration' process focussing on “gray” values which are defined colorimetric terms (Lab) instead of densitometric ones by what they describe as a Neutral Print Density Curve (NPDC) (www.gracol.org for more details). GRACol also offers a strategy for 'distributed' certification by providing training to third parties who then become G7 certifiers.
The documentation supporting the G7 process on the GRACol website explains their prescribed methodology for setting up and achieving ISO compliant results using a single set of characterisation data. “The 'G' refers to calibrating Gray values, while the '7' refers to the seven primary color values defined in the ISO 12647-2 printing standard; Cyan, Magenta, Yellow, Black (K), Red (M+Y), Green (C+Y) and Blue (C+M). According to this documentation “The two most widely-promoted characterization data sets for commercial printing come from FOGRA and GRACol 7.” (p7, Calibrating, Printing and Proofing by the G7 Method, 2006.) In fact, the original (beta) version of the GRACol data was an adjusted version of the FOGRA data. In other words, it built on the work already done by FOGRA.
We could include other, ‘independent’ service providers who provide certification in ‘proficiency’ with respect to ISO compliance however, the distinction should be made between those offering certification that is approved or supported by industry-wide organizations and those that are one-to-one contracts between the printer and the service provider who may or may not use G7 methodology, recommend PSO, or use the FOGRA characterisation data as the basis for building their own ISO compliant profiles.
The important thing to remember is that they all offer slightly different paths to the same destination: compliance to the ISO standard 12647-2:2004/Amd 1:2007.
The TC 130 and our web site are not here to
promote one method over another;
merely to illustrate the differences between ISO standards, what they contain, and the options available for achieving results that comply.
In summary, the options for achieving compliance outlined so far are:
- Self – compliance: You
set up your workflow, educate your workforce, use consistent and
compliant materials, develop your own ISO compliant profile, monitor
the result and issue your own product guarantee. You could even issue
your own certificates!
- Client driven. Your client(s)
demand samples of your product (proofs and press sheets). They submit
them to tests and measurements. They may employ a third party to do it
for them or, if they are large enough they may employ their own experts
to enforce compliance on their suppliers. This is a major concern for
large consumers of printed material that is sourced from a variety of
printers. This is what happened in Europe which initiated the research
and development carried out by FOGRA/BVDM that lead to the development
- Third party certification: A third party (organization/service provider) offering certification, or its agent, is contracted to supervise the implementation of a workflow that produces ISO compliant product. In effect, the organisation certifies the printer and the client accepts the certification as proof that the product is compliant.
We trust that this explains and simplifies the available options for achieving compliance with ISO 12647-2. Please refer to the accompanying flow chart in this section and use it when explaining the “pathways to compliance” to your staff.