At ColorMetrix we have some new and potential new customers who will be using our products (both ColorMetrix and ProofPass.com) to monitor and control digital presses like the HP Indigo, Xerox 8000, and NexPress. During our sales presentations most of these folks have expressed concern that the device is constantly self calibrating and correcting itself, so why would I need to do external process control?
My short answer: “Do you really want to let the fox watch the hen house?”
For the most part the internal controls on digital presses are built to keep the device in calibration. While these devices are different than conventional printing presses, they are not so different that we conventional printers do not understand them. There is a certain amount of variation that a conventional press self adjusts for like automatic register controls and the like. So, if we follow this augment to a logical conclusion that would mean process control would be useless on a conventional press as well. If you are reading this article I am fairly certain you do not believe that.
In general the act of process control requires the user to view the device (press in our case) as a black box. By measuring the resulting print the device produces, we are taking into account everything that happens in the device and the environment the device is in.
For example, several of these devices ‚Äúself-calibrate‚Äù by imaging on a drum or a belt between actual substrate impressions. It seems to me we have removed a pretty important piece of the quality puzzle from that equation. What if our substrate is stored in a warehouse with no air conditioning and our press is in a climate controlled room? A week or so ago it was almost 100 degrees with very high humidity in the mid-west. If we bring that paper from the warehouse into the production room and do not provide 24 hours for the paper to acclimate, do you think we would get the same print result as we would with paper that had been acclimated?
If you said NO, please call me for a free trial version of ColorMetrix or ProofPass.com so you can measure it yourself.
In conclusion, all the variables that contribute to a printed piece like; faulty RIPs, toner changes, device wear and tear, paper changes, etc are viewed by a process control system like ColorMetrix as a black box. Process control systems like ColorMetrix measure the finished piece in order to accomplish two goals:
- Confirm that the finished print quality is within acceptable quality guidelines
- Provide detailed enough information to track back the problem portion of the process when #1 above is not achieved
Overall, the goal of the manufactures self-calibration procedure to stability of the imaging process itself. The goal of a system like ColorMetrix is overall print and color quality of the printed piece you put in the hands of your customer.