After eight years of discussions, the revision of the ISO 12647-2 standard on offset printing is taking shape. The ISO TC130 WG3 technical committee has finally reached a compromise on the revision of ISO 12647-2, which governs the control of offset printing processes. The currently applicable version dates from 2013. A draft international standard (DIS) is expected to be published by the end of 2026, ahead of a final vote in 2027. According to Fogra, the German research institute for printing technologies, this draft is expected to be adopted without any substantive changes.
Three categories of printing conditions
The new version distinguishes between three types of print conditions: native, saved, and relative.
Twelve native conditions, corresponding to the most commonly used substrates, will be directly defined in the standard along with their target values. These include the conditions associated with Fogra51 and Fogra52, used for coated and uncoated sheetfed offset papers, respectively. For coated papers, however, the target values for black dot gain in midtones have been increased by 1.5%, according to the institute.
The registered conditions correspond to printing conditions that have been fully characterized using a test chart and listed on the International Color Consortium (ICC) website. They also include the unmodified Fogra51 profile as well as the older heatset web offset printing profiles, which are still recommended by Fogra and the ProcessStandard Offsetdruck (PSO).
Finally, relative conditions apply when the paper white differs from that of a native or registered condition. In such cases, the target colorimetric values must be recalculated. The conversion formulas are available as Excel spreadsheets on the Fogra website and are already integrated into common measuring instruments and software.
Three Possible Calibration Methods
The other major change concerns press calibration. This will no longer be based solely on the density of solid areas and dot gain measured according to the Murray-Davis method.
Two additional methods are now planned.
The first method uses ?CTV (Color Tone Value) colorimetric values, which measure the difference between the colorimetric tone value measured on the printed material and the target value. Based on the visual perception of colors, this method can promote a more consistent reproduction of gradients. Fogra, however, recommends caution, as there is not yet sufficient experience with its use in production.
The second, Near Neutral Calibration (NNC), serves in particular as the basis for the American G7 method. It adjusts the tonal reproduction curves to achieve defined colorimetric values near the gray axis, without imposing fixed dot gain values. These are individually adjusted to obtain defined colorimetric coordinates for overprints close to the gray axis.
The institute favors the Murray-Davis and ?CTV methods, which are considered less complex and better suited for analyzing printing defects.
"For practical purposes, it should be noted that different calibration methods can lead to different print results. Similarly, a print may comply with the standard according to one method but not according to another. It is therefore important to clearly define in advance which method will be used." Fogra points out.
Modified colorimetric tolerances
The revision also changes the measurement conditions. Target values will now be defined solely against a white background. For measurements against a black background, they must be calculated based on the paper?s opacity.
The color variation tolerances for spot colors are standardized to ?E*ab = 5. The additional criterion ?H*ab is eliminated. For dot gain, the midtone range is extended to 70%.
Fogra62 and New ICC Profiles
For sheetfed offset printing on coated paper, new universal characterization data?known as Fogra62?have been developed to ensure consistent print results, regardless of the calibration method used.
Print tests have shown that existing standards for coated papers are very close to this new reference. According to Fogra, printers receiving files prepared using Fogra51 and Fogra62 will therefore not necessarily need to maintain two separate calibrations.
The European Color Initiative (ECI) has already created and successfully tested an ICC profile based on this new data. International discussions are ongoing to publish a common profile for the new PC1 printing condition. No final agreement has been announced yet.
