Defects in print images, for example due to scratches, hickeys, or smudging, are irritating and lead to complaints. While packaging printers can get by with random checks, up to now they only had a choice between two sub-par solutions to deliver impeccable quality for coloring and print image: auxiliary equipment procured specifically for detecting image defects or online color measurement systems that are upgraded for this purpose but need a lot of time or even a second measurement process. One alternative is inline inspection systems. Although these detect even the smallest defects on each sheet, a complete inspection of the entire print job is not always absolutely necessary.
“With many premium packagings, for example for beverages and cosmetics, the missing comma in the 4-point writing is less important than an overall impression for the packaging of flawlessness and color accuracy. Random control measurements are usually perfectly adequate for this,” says Bernd Utter, Product Manager Color Measurement Technology. This is where Prinect Image Control 3 with the “Offline Inspection” option comes in.
Prinect Image Control 3 can do what other systems cannot: spectrally scan the entire sheet. This capability gives it the edge when it comes to print image control, both in terms of coloring and defects: “The printed sheet only needs to be measured once. This means no second measurement or even transporting the sheets to another location. The time saving is 2 to 5 minutes per sheet in 75 cm x 106 cm format,” explains Utter.
Added to this, the defect analysis runs on a separate computer. This means that image defect detection and color measurement can take place in parallel. Prinect Image Control 3 transfers the measurement data to the inspection software for this. While the software handles the image defect detection in the background, Prinect Image Control 3 can already be scanning the next printed sheet within 25 seconds at full speed.
The second key benefit emphasized by Utter is the extremely precise measurement of the print image from the leading edge of the sheet to the trailing edge: “Prinect Image Control 3 generates a 200 dpi scan. This extremely high resolution with 50 million measuring points not only ensures completely true color image control over the entire sheet, but also guarantees a high inspection quality for each repeat in the print image.”
If a defect is detected in the print image, it is immediately displayed on the Wallscreen of the printing press. The printer decides with a click of a mouse whether the scanned sheet should be compared with the PDF file from prepress or with a good sheet or full-sheet proof prepared beforehand. This option provides maximum flexibility. It is also possible to switch within a print job.
An image defect report is created for each inspection. This is automatically saved and can be evaluated after the end of the job together with the color report, also generated by Prinect Image Control 3 for the purpose of production optimization.
The solution is operated conveniently on the Wallscreen of the Prinect Press Center machine control station or on a separate screen. The necessary reference data is automatically provided via the digital Prinect workflow. Integration into other popular packaging printing workflow systems is, of course, also possible. A particular highlight is that the printer can adjust the inspection accuracy without having to scan the sheet again. This means an enormous time advantage when dealing with critical motifs or poor substrates.
There are also other beneficial features for printing companies. For example, Prinect Image Control 3 is the only color measurement system on the market to offer the ability to measure and control the opaque white using a completely normal print control strip. “Reliable control of opaque white and chromatic colors when printing on film or aluminum-coated cardboard easily saves 400 to 500 sheets of paper waste per job,” reports Utter.
Users of Prinect Image Control 3 also enjoy free access to the color tables for PantonePLUS®, HKS, and FOGRA51-52/PSO. There is also a connection to the central color database in Prinect Production Manager, where new colors can be uploaded in CxF format. The color data is immediately available to all users in the company.
“Offline Inspection” can be retrofitted quickly and easily by simply activating the option. “Offline Inspection” is not only a high-quality solution but, thanks to the elimination of costly auxiliary components for Image Control 3, also an inexpensive solution for efficient and reliable inspection in packaging printing,” sums up Utter.
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