Spectral colorimetry in commercial printing

Spectral Colometry

New, inline, and compliant with M1

As the market leader in commercial printing, manroland web systems has installed over 5,000 measuring heads for its InlineDensity Control color control on the market. For these customers, it is a simple retrofit solution to meet the higher demands of spectral measurement (ISS) as a plug-in to IDS. Ink on the press can be optimally controlled based on the combination of real density and spectral values, recorded with separate cameras. The spectral color measuring unit from grapho metronic is the only one to meet the M1-measuring conditions for inline measurement and detects optical brightening agents by activating a UV LED.

Commercial printing faces an increasing degree of automation on all levels, including quality assurance through color measurement. More and more printshops have to present their customers with spectral values as proof of quality. Large retail chains in particular are extremely quality-conscious in this area. Random sample results taken offline in proofs and during production runs are no longer sufficient and have been labeled as inadequate. In contrast, spectral color measurement with InlineSpectral System (ISS) presents major advantages: Uniform real-time measurement in the printing process saves time, improves color stability, reduces waste, and offers comprehensive proof of the system’s quality. In short, offline color control with a manual spectrophotometer on cut-out material can no longer be the standard.

Localized measurement

Print standards based on colorimetric measurements are playing an ever more important role in everyday production. The ISO12647 standard family deserves particular mention. The colorimetric measurements support printshops in providing verification of having achieved a target print standard within a specified tolerance range in print production. With color control by means of colorimetric measurements, colors can also be better matched between target and actual values defined by a print standard. Within strict tolerances, this is only possible with localized, high-resolution spectral measurement.

ISS: like no other

ISS is automation’s technical response to increasing demands on quality. Within the framework of digital spectral color communication, the measuring technology meets the highest requirements and achieves a significantly higher measurement resolution than other systems with its 256 measuring channels. ISS offers real spectral measurement and thus comparable, resilient color locus measurement at full process speed. The spectral sensor can measure color fields across the entire width of the printing area. The spectral measurement automatically detects marks with a supplementary image sensor, as well as the measurement position via image analysis.

The M-factor

One challenge of many modern paper types is optical brightening agents. In response, color communication defined new standards. ISO 12647-2:2013 defined new measuring conditions (M0-M3). Measuring condition M1 is intended to reduce deviations of the device measurement results due to fluorescence. This applies to both fluorescence due to optical brightening agents in the paper as well as the fluorescence of coloring agents that are used for imaging or to create proofs. Unlike measuring condition M0, M1 precisely defines the UV component in the lighting. The production process requires just this type of measuring instrument according to M1 to meet the requirements of ISO 12647-2 in practice. The inline spectral photometer featured in ISC is the first and only one to measure in accordance with M1.

Full integration into PECOM-X

Whether in new commercial printing presses or as an upgrade: ISS is integrated into the controller. In addition to the InlineDensity Control modules, the system performs simultaneous densitometry along the entire width of the printing area. The sensor measures point by point and traverses across the direction of web travel. Weighting of the quality parameters enables the differentiation of various control strategies. Printers always have a good overview, with the color space achieved in print displayed on the user interface. The determined density/color distance correlation per color is included in the process data and ensures a sustainable increase in color quality in webfed printing.

ISS highlights:

    Real, high-resolution spectral measurement
    Production measurement system with M1-measurement condition
    Integrated image sensor
    High-quality components and precise unit adjustment
    Convincing lighting concept with high performance LEDs and controlled UV intensity
    Precision thanks to temperature compensation and integrated white tile with protective cover
    Compressed air circulation (protection from contamination and cooling function)
    Long service life thanks to flash mode

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