Calibration of a single printing device is not always the easiest task, and matching multiple printers to one another is an even bigger challenge.
Three Key Things To Matching Multiple Printers
One question that has come up frequently is “what is the best way to profile multiple devices of the same model?” If you are trying to achieve a close visual match between printing devices, there are three key things to consider:
1) Printer gamuts have to be pretty close between devices. This has a lot to do with substrate texture and ink texture.
2) It is necessary to evaluate more than just the worst ∆E value. You need to know how all the patches in a control strip compare in ∆E, not just the worst or the average. When choosing a control strip,the more patches, the better, as long as the chart doesn’t become too large for practical daily use. The more patches under 1 ∆E, the more likely the printing is visually close.
3) You can’t compare to an industry reference, like GRACoL, when visually comparing devices. You have to compare one device as the reference to the other because that’s what you’re looking at in the viewing area. You can’t see GRACoL, as there is no perfect GRACoL proof. But you certainly can see the difference between printer A and printer B. So make printer A the reference when comparing those two devices. Hopefully with grouping tests you can compare multiple devices to one device.
Calibrating The Device
Tight calibration of the device and the ability to truly recalibrate back to the same known state is key.
From my experience, the automated “recalibration” process does not always work well in the field. Some RIPs are better than others. The bottom line is for true recalibration to work it has to be a two-part process.
First, you have to achieve the same solid ink value that was in the original calibration
Second, you have to then create the same curve along the values between 0% and 100%.
Most RIPs do the latter, but few actually do the former during the automated recalibration process. If you can’t fully recalibrate the printer, the original profile is eventually going to be too far off the mark.
A Single Profile Doesn’t Always Work For Multiple Devices
Also consider that very rarely do two of the same devices that are the same age print the same color out of the box.
I’ve proven this many times when evaluating color output data during calibration sessions. There is no way to successfully use a single profile for multiple devices that aren’t even close to a tight visual match.
My advice is to target the same source reference space (GRACoL as an example) for each device. Then calibrate and profile each device as carefully as possible to achieve as tight a match as the RIP can provide.
When finished, you can compare how close each device is to one another by printing a test chart and comparing the measured results. RIPs that have iterative optimization have a much better chance of achieving a tight calibration between multiple devices.
Run Comparison Tests For Matching Multiple Printers
You certainly can and should run comparison tests between all your devices (ideally on a single substrate all devices can print on) to identify which devices are the closest to one another and group them accordingly.
The point here is to get to know each and every device (it’s gamut, how consistently it prints, etc.). Maybe you get lucky and find several devices that actually are close enough to calibrate using a single profile. Only after going through the process of calibration and evaluating the results can you truly know the color capability of each device.
I have installed many pairs of Epson aqueous printers and have never found two that calibrate the same or profile the same, however, following the process described above will get them to the closest possible visual match.
SpotOn Verify is the ideal tool for comparing the calibration results of each printing device. SpotOn Analyze is the ideal tool for setting ink limits and examining the color differences between each printing device. Try them for yourself!