Notes on the development of ISO/TS 23031

The development of ISO/TS 23031 Assessment and validation of the performance of spectrocolorimeters and spectrodensitometers followed a somewhat unusual and circuitous path through the ISO document development process.  However, it all began rather innocently, at the spring meeting of ISO TC 130, which was held in May 2015 in Bologna, Italy.  At that meeting an expert from the UK Delegation had prepared a brief proposal, more of a request actually, tabled as document N1697*, "UK Proposal for new work item".  The proposal was titled, Inter-Manufacturer / Instrument Agreement – Calibration and Servicing.  It stated that the request had arisen from issues uncovered by the Steering Committee for the British Printing Industries Federation (BPIF) ISO 12647 certification called Colour Quality Scheme, in which conformance to the requirements of the various parts of ISO 12647 mandates that all instruments used to assess conformance should recalibrated and serviced according to the manufacturer's requirements.  It further stipulates that all laboratories performing such work must be certified to ISO 17025 Testing and calibration laboratories.  However, only a small number of organizations in the world can afford to operate an ISO 17025 testing and calibration laboratory.  Thus, a clear need for an international document was identified, a document that would describe a common methodology for calibrating and validating spectrophotometers, spectrodensitometers and spectrocolorimeters that are used in the production of printed coloured images. The UK delegation submitted two additional documents during the meeting. which were tabled as N1708 and N1709. WG3 document N1708 was a PowerPoint presentation by expert Dr. Kiran Dispande that documented the many sources of variations in the instruments in use in the field for controlling the colour of printed images.  The presentation made a quantitative case for the accumulation of uncertainty, even within an identical instrument due to the standard optional modes for collecting data.  It concluded by stating, "Uncertainty of colour measurement is a major issue for colour management in the production environment."  Furthermore, the performance specifications published by the instrument manufacturers, repeatability, reproducibility and inter-instrument agreement, are based on the conditions of a metrology laboratory and do not represent real-world conditions. 

Danny Rich
Danny C. Rich is the Senior Color Physicist for Sun Chemical Corporation, USA. He is trained in optical physics and optical metrology. Currently he leads the Color Research Laboratory and studies the technology of measurement of the materials incorporated in graphic reproduction. Beside his work in TC 130 he is also active in TC 6, TC 42 and the ICC.

Document N1709 was a further description of the current condition of instrumentation and metrology for the measurement of light and colour in the graphic arts industry.  It pointed out that the poor level of agreement often made it difficult to apply the numerical techniques developed by the experts in WG3 for process control and colour management.  One possible solution would be for ISO to insist that all parties involved in the reproduction process utilize a single vendor, make and model while an alternative would be to take a single vendor's instrument and standardize the design, thus forcing all other producers to license and construct that design.  These were not only deemed unreasonable, but strongly violate the ISO rules on these matters.  It was suggested that there needs to be training and direction on how critical measurement properties, such as repeatability and inter-instrument and inter-model agreement, can be determined and validated in the field by the users of ISO WG3 documents.  Document N1709 then cites Professor John Seymour, from the School of Graphic Communication at Clemson University, who has indicated that the requirements of ISO 13655 cannot be verified because there are no relevant certified reference materials for this application.

Very shortly after the meetings in Bologna, in the summer of 2015, the Japanese Delegation filed a response supporting the UK proposal .  This response was tabled as document N1710 and contained the thoughts of the design engineers at Konica Minolta, a global manufacturer of instruments for the measurement of light and colour.  It further emphasized that there is no international standard with an agreed upon method to trace "colour measurement" back to an international scale.  Such a scale would require equivalence among the national scales by evaluating and correcting the differences between these scales.  At the present time, only the spectral reflectance factors of white materials have been studied.  The Japanese agreed that it was important to define what inter-instrument agreement and inter-model agreement levels are suitable for the graphic arts industry and that, to do this, it is necessary to specify some test methods for these properties for the graphic arts in the form of an International Standard or a Technical Specification.

At the close of the meetings in Bologna an Action Item (15/10) was created to develop a study group composed of 10 experts from seven p-member countries to draft a proposal on a way forward and present it to WG3 and ISO TC 130 at plenary meetings to be held in the fall of 2015 at Seoul, South Korea.

At the meetings in the fall of 2015, the Action Item was completed and was carried forward to the spring 2016 meetings to be held in Berlin.  At these meetings, Danny Rich presented a first draft of a new preliminary work item titled "Assessment and validation of the performance of spectrocolorimeters and spectrodensitometers".  This document was tabled as WG3 N1815. The PNWI (Preliminary New Work Item) document addressed all of the issues identified in the earlier presentations and included descriptions of two types of reference materials, the ceramic tiles favoured by the instrument makers and a printed sheet with a high level of OBA (Optical Brightening Agents) favoured by the pragmatists.

While this document was placed on the agenda for the fall 2016 plenary meetings, it was not considered as the project leader was also the project leader on the revision  of ISO 13655, part of JWG8 with ISO TC 42.  The leader was not able to draft and edit two documents at the same time and maintain his regular work schedule.  The start of the PNWI was put off until the balloting on ISO 13655 was completed.

Form 04 on the PNWI was finally filed in the summer of 2017 at the meetings in Toronto, Canada.  The editor was then charged with preparing a NWI (New Work Item) ballot from an expanded and improved working draft.  The editor fought the committee to prevent scope creep as, at each revision, some new measurement system was proposed to be added, many of which were poorly defined and only rarely used in the graphic arts.  During the meeting the editing committee had agreed that, as this was a new type of document for ISO TC 130 and as there are no certified reference materials and international scales to which measurements might be traced, it would be best if the document was proposed as a Technical Specification (TS) and contained procedures and instructions, but made no requirements on the level of performance to be expected from these tests. This is the main difference from an International Standard, which would contain such requirements.

A WD (Working Draft) (N1956) was submitted as an NWI ballot for ISO/TS 23031 in August of 2017 along with a revised Form 04 (N1957).  The ballot was approved but received a large number of comments.  The comments were sorted and resolved and the ROC (Resolution Of Comments) was prepared in November of 2017.  After the document had been edited and the comments applied, a new ballot was issued.  That ballot was also approved and again the comments were sorted and resolved, in April of 2018 just prior to the ISO TC 130 meetings in Berlin.

The comments were discussed at the Berlin meeting and the ROC were revised and re-issued in July 2018.  After the spring meetings, the editing committee and Working Group 3 convinced the editor to change the document to a Technical Report** from a Technical Specification.  This was to make the document more descriptive and less prescriptive.  The WG was struggling with how to format and draft this document that was to provide both education and direction without overstepping the bounds of free trade.

A new ballot, as DTR (Draft Technical report) 23031, was prepared in September 2018.  Again, the ballot was approved but received many comments, mainly about the structure and the inclusion or exclusion of requirements.  A TR should not have requirements, but merely report on the state of a technology.  Another ballot was sent out in February 2019 and this also passed but still had technical comments that had to be resolved.  As a Technical Report, the ballots could go out more quickly and  another ballot was issued in May 2019.  This ballot also passed but still with a few comments.  During these months, the editing committee held a series of meetings at locations in the Far East, including Fall 2018 in Tokyo and Spring 2019 in Hong Kong.  The editor was not able to travel to these meetings and the ROC meetings were held via WebEx.  However, the fall 2019 meeting was held in Lehi, Utah, USA and the committee was able to meet with the editor once again.

At the fall 2019 meetings, the issue was once again raised that a Technical Report might not be the correct format.  A further revised ballot on the DTR was issued in September of 2019 and it passed and the comments and requested edits were resolved by the beginning of November.  The ISO HQ Editor was contacted.  After reading the document, the ISO Editor agreed that the document should not be a Technical Report, but commented that the document, in the draft version, was perfectly OK to be published as a Technical Specification.

The editing committee met once more to request a change of the document from DTR back to DTS.  The ballot went out in December 2019 and was returned by March 2020.  The ballot was approved with only minor comments and the final draft TS was submitted for a ballot in May 2020.  After a month, the approved document was edited for the last time and a publication draft was sent to the ISO Editor.  The Editor recommended a few minor editorial corrections and clarifications, which were made, and the final publication was released in July 2020.

In reviewing the steps of drafting and publishing a completely new type of document, be it an IS (International Standard), a TS (Technical Specification), a TR (Technical Report) or a Guide (ISO documents can be for guidance only), can be very challenging.  With documents that are similar in form and style to existing standards, the modifications are more obvious and the editing focuses on the content and not so much on the structure.


Respectfully submitted

Dany Rich signature
* All documents used in a working group are numbered and documented in the ISO work. They are referred to as “N-documents” and listed here for anyone who likes to trace the path to the published Technical Specification.

** There are four main types of publications produced by ISO. Those are IS (International Standard), TS (Technical Specification), TR (Technical Report) and finally Guidance documents.