The standard provides objective targets to assess the quality of a newspaper. If anyone is not happy with the quality of production of a newspaper or with the quality of a particular newspaper ad, the ISO 12647-3 standard provides reliable assessment criteria to check whether the quality of the print satisfies certain technical conditions. Therefore, it is easy for a newspaper to continuously assess their print quality and improve.
Like any ISO norm, ISO 12637-3 is rviewed once in five years to include latest technological developments in newspaper production and the customer expectations from newspapers. This article summarises the revisions in ISO 12647-3 that came into effect in December 2013.
The next International Newspaper Color Quality Club 2016-2018 (INCQC) will have appropriate modifications in the competition evaluations in-line with the revised ISO standard. The popular on-line self-check tool of WAN-IFRA has already adapted some of the revisions.
The first important point is the allowable color differences of the secondary colors (RGB), which are now no longer informative but normative. It means that the Delta E tolerance of Red (M+Y), Green (C+Y) and Blue (C+M) are binding. The permissible variations in color overprints of M+Y, C+Y, and C+M should not exceed 8 Delta E.
At this point, it should be noted that the revised standard, in addition to Delta E 1976, has also included tolerances according to Delta E 2000. Delta E 1976 is a simple formula, calculated as the distance between two points in the three dimentional space. Delta E 2000 is a superior formula for calculating color difference. However, it is complex. We should note that the tolerances specified for Delta E 2000 is only informative in the current revision of ISO 12647-3. Hence, for the WAN-IFRA ISO certification, we will follow the Delta E 1976 formula, since this is normative.
Secondy a slight adjustment was made in the color values of magenta (measured on black backing). Instead of –2 b*, the new target is now at –1 b*. Thus Magenta is slightly less bluish or something more neutral. This change brings magenta closer to reality and will certainly be appreciated by printers, pigment and ink producers.
The third significant change is with regard to Total Ink Coverage (TIC). The maximum total inc coverage (CMYK) was reduced from 260% to 240%. Further, the standard recommends 220% TIC for newspaper printing. Highest TIC should be composed with at least 90% black ink (K) instead of a previous minimum of 85%. According our certification experience implementing this change should not be a problem considered a modern image workflow technology in place.
Color register accuracy is an important criterion for the evaluation of printed newspaper copies. The decisive factor for consumers is the so-called diagonal register, so the total distance (hypotenuse) between the 4 color separations is the combination of circumferential and lateral mis-register. So far, ISO specified a maximum of 0.30 mm tolerance and a (non-binding) recommendation of 0.15 mm maximal tolerance. This target is now obsolete. Instead a new normative tolerance limit of 0.20 mm is specified, tthere is no other recommendation any more.
Another major novelty of the new revised ISO 12647-3 newspaper standard is the introduction of a single standard deviation for the evaluation of different parameters and their tolerances. To be in line with the ISO standard, it is sufficient if 68% of all samples are within the required tolerance bandwidth. This means that in a test run undertaken during the on-site audit, many printed samples have to be evaluated and if 68% of them are in conformance with ISO standard the newspaper will qualify for certification. The increase of measurement efforts will lead to a slight price-increase for certification candidates.
In the area of screening, there are slight adjustments following the current technology. Earlier, the recommended screen frequency was set to 40 lines per cm. Now the screen frequency allowed can be 40 or 54 lines per cm. There is no change in the specification of screen angles. As far as the certification is concerned, points are deducted only if there is a visible disturbing moiré or easily visible dots (rosette). The minimum resolution allowed for CTP was lowered to 393 lines per cm. In practice this will only be relevant in a few special cases.
Some minor changes are specified for the 26% dot gain curve. The changes are not significant as they are intended only to smoothen the dot gain curve and the changes are in decimal points. The adaptation is not absolutely necessary. For those who want to perform this adjustment to the new norm, it can be easily carried out if they have the target curve stored separately as “Intended Press”. The 30% curve, which was earlier allowed for North America is eliminated and hence there is only one global newspaper standard curve now.
The tonal range was earlier specified between 3% to 90%. Again there is a slight correction to 3% to 95% now. This means that there should be good reproduction of highlight and shadow details, which can be easily mastered with modern machinery and technology.
Regarding newsprint properties, the ISO standard of 2005 only specified “Paper shade”. In the latest revision, two additional paper parameters were included – Basis Weight and Gloss. WAN-IFRA has always recommended news publishers to test their newsprint regularly for their basic, optical, mechanical and printability parameters. Testing the materials provide exact details on how the raw materials will behave during production. However, the two (above mentioned) informative parameters specified in the new norm do not have much effect on color quality of print and hence will not be considered for certification.
The INCQC model to evaluate gray balance was adopted by ISO. It is very useful to check print quality. For human color perception in newspaper printing, the paper shade and the darkest black (4c black) are taken as the reference points. These two points are connected by an imaginary line and they represent the gray axis. The axis-points are perceived as neutral by the observer. Since, the shade of the newsprint is slightly yellowish and not neutral, this imaginary gray axis is also not perfectly neutral. However, human eye, when it perceives a printed newspaper, adapts to the newsprint shade and considers it as neutral gray.
The gray balance combinations specified in ISO 12647-3:2005 were widely used by INCQC and WAN-IFRA ISO certification. These combinations produce shades that appeare neutral to the eye. Hence, we see no reason to move from these proven combinations to the new (informative only) specification in Annex B of the revised standard.
Moritz Schwarz, Senior Consultant at Kirchner + Robrecht management consultants. On behalf of WAN-IFRA, he performs WAN-IFRA ISO Audits and certification projects.
Manfred Werfel, WAN-IFRA Deputy CEO
Executive Director, Global Events