Thanks to the Digital Press Colour Standard, a new system introduced to South Africa by Acme Graphics, digital press colour management efficiencies can be dramatically improved.
DIGITAL press operators should not be allowed to use their presses as proofing devices or to manipulate colour. They are simply responsible for ensuring the press is calibrated and to run production.
According to Hauke Liefferink, MD of Acme Graphics, Acme’s patented Digital Press Colour Standard is a world first in many ways. It’s a single PDF file, with portions that are colour managed to simulate a standard such as ISO Coated V2 and ink channel targets that are not colour managed, allowing a single page report that can be used for selecting colour, checking calibration of the press and to serve as a Master Colour Standard to be filed in a work ticket.
Explains Hauke: ‘Using only nine blocks, it’s able to show the press operator the only choices available for a spot colour. It’s simply gang printed with the stepped up file just prior to the production run.’
Since this nine-block grid chart is built in 3D in the Lab/LCh colour space, using a patented method, it’s much more efficient in showing practical options or ‘flavours’ of a spot colour. Current grid charts are not built in 3D Lab/LCh colour space and rely simply on addition or subtraction of tone, resulting in a large, inefficient arrangement of swatches.
‘Previously, grid charts showing options of a spot colour were large in number and time-consuming to interpret,’ Hauke continues. ‘These nine blocks show only the useful choices and are arranged around the colour wheel. Current grid charts have no useful arrangement.’
There will always be a need to visually select many spot colours, since the algorithm used by spectrometers to make colour decisions (Delta E) is an approximation of how the human eye sees colour and is not always accurate, especially in grey and pastel spot colours.
‘Ultimately,’ Hauke contends, ‘presses that have online spectrometers can also benefit from this method with much faster scanning from fewer swatches. One of the most widely used Delta E formulas (CIEDE2000) does a wonderful job of describing colour difference in some colours and a less than satisfactory job in others. That’s why visual approval or selection of colour remains critical.’
Acme’s Digital Press Colour Standard works hand in hand with the existing colour management system on a digital press. It is simply a report layer that sits on top of the existing system.
