Mottling u digitalnomm tisku

MOTTLING IN DIGITAL PRINTING

Gorazd Golob, Primož Wiengerl, Aleksandra Bernašek, Aleš Hladnik

Sažetak

Jedan od primarnih aspekata kvalitete tiska je neujednačenost tiska, također znan kao mottling tiska. Mottling u tisku može se definirati kao nehomogenost na tvrdoj tiskarskoj podlozi zbog varijacija u refleksiji tiskarskih podloga. Naglasak se stavlja na uočene nehomogenosti, gdje percepcija često nije u linearnoj korelaciji sa fizičkim karakteristikama tiska. Stoga se karakteristike i ograničenja ljudskog vidnog sustava (HVS) moraju uzeti u obzir kada se dizajniraju instrumentalne metode za procjenu tiskarskog mottlinga.
Predloženo je nekoliko metoda za evaluaciju mottlinga. Usprkos sličnosti u određenim segmentima one se razlikuju u osnovnim principima, razmatranje ljudskog vidnog sustava i njihove kompleksnosti[2, 3, 5, 6, 7, 8].
Cilj našeg istraživanja je bila evaluacija mottlinga u tisku napravljenih na dva različita elektrografska uređaja. Evaluacija je ostvarena ljudskom vizualnom procjenom putem pripremljenih uzoraka te s instrumentalnom metodom baziranom na analizi slike i filtriranju učestalosti domene.
Ključne riječi: mottling u tisku, vizualna procjena, elektrografija, analiza slike

Abstract

One of the primary aspects of print quality is unevenness of prints, also known as print mottle. Print mottle can be defined as perceived inhomogeneities in the solid print area due to variations in the reflectance of the printed surface [1]. The emphasis is on perceivedinhomogeneities, where perception is often not in linear correlation with physical characteristics of the print. Therefore, properties and limitations of human visual system (HVS) must be taken into consideration when instrumental methods for mottle assessment are designed.
Several methods have been proposed for evaluating print mottling. In spite of similarity in some segments, they differ from each other in basic principles, consideration of HVS and their complexity[2, 3, 5, 6, 7, 8].
The purpose of our research was to evaluate mottling on prints made with two different electrophotographic printing systems. Evaluation was accomplished with human visual assessment and with an instrumental method, based on image analysis and filtering in frequency domain.
Key words: print mottle, visual assessment, electrophotography, image analysis.