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Labels as a graphic product are important for information in declarations, especially for languages of smaller nations. Labels are increasingly required together with their ever more complicated technical performance, one of them being the desire to adapt the text to blind or partially sighted users. We therefore tested the possibility of using a declaration text in black with overprinted Braille cells with no or minor influence on legibility. The research was performed by analyzing the influence of printed cells on the achromatic halftone reproduction. The prints of the text and the overprinted Braille cells were made with a UV LED inkjet printer. Two different typefaces in two different sizes suitable for labelling were tested. The color properties were determined colorimetrically and the differences in the typographic tonal density of typefaces were measured with an image analysis. The legibility research was performed with the help of observers who read the plain printed text and the printed text in combination with overprinted Braille cells made with varnish. The results showed that an appropriate typeface and type size can reduce the influence of overprinted Braille on text legibility.

For high-quality black & white printing realized with an electrophotography printing machine, it is necessary to prepare the printing substrate. For optimal adhesion of the black liquid electrophotography ink to the printing substrate, it is necessary to apply additional treatment to meet ideal substrate surface tension by means of corona treatment and/or coating with fluid for regulating the surface tension (primer). This paper examines the influence of the corona power and the thickness of used fluid for the regulation of surface tension on the achromatic digital reproduction quality. Within the electrophotography printing process, this implies determining the differences in the colour gamut volume, the structure of characteristic screening elements, the amplitude-modulated screening, and the increase in the number of colour separations. The results show that the optimal colour tone values, colour gamut, and dot gain, high quality of digital prints will be realized without the use of the fluid for the regulation of surface tension and without activation of the corona power. That confirms that the FOGRA values for industrial standards can be used for quality electrophotography printing.

Različit broj otisnutih slojeva bijele boje utječe na čitljivost otisaka. U ovom radu testirana je mogućnost postizanja najbolje čitljivosti otisnutog teksta na etiketi, zajedno sa analizom tipografskih svojstava i ostvarenih kolornih promjena. Otisci otisnuti na UV tintnom pisaču imaju mogućnost ostvarivanja većeg broja istih separacija (tri sloja bijele). Pritom su varirana tri tipa i četiri veličine pisma (karakteristična za etiketne deklaracije). Kolorne promjene su određene kolorimetrijski, te izračunom tipografske optičke gustoće slova primjenom slikovne analize. Ispitivanje čitljivosti je izvršena uz pomoć ispitanika koji su čitali tekst u kombinaciji: bijela podloga – crni tekst i crna podloga – bijeli tekst. Rezultati pokazuju da bez obzira na ostvarene kolorimetrijske promjene i različitu kvalitetu tipografske reprodukcije, najbolja čitljivost je ostvarena tiskom u dva sloja., A different number of white ink layers printed with the inkjet technology can influence the legibility of prints. Therefore, we tested how to achieve best legibility of printed text and labelling information, considering the changes in colorimetric and typographic properties. The prints were made with an inkjet printer and three different numbers of white ink layers were used. Three different typefaces in four different sizes, appropriate for labelling, were tested. The colour differences were determined colorimetrically and the differences in the typographic tonal density of typefaces were measured with an image analysis. The legibility research was performed with the help of observers who read the printed text in the combination of white ink on black paper and black ink on white paper. The results led to the conclusion that with regard to the colorimetric and typographic quality and effectiveness, the legibility was the best at two layers of white ink.

U elektrofotografiji s tekućem tonerom, kolornigamut je često smanjen u žutom području što vodi do problema pri realizaciji otisaka fotografske kvalitete. Poznato je da koncentracija čestica pigmenta u tiskarskom bojilu i debljina nanosa na papirnatoj podlozi utjeću na konačnu kvalitetu otiska. U ovom radu varirana su upravo ta dva parametara, primjenjujući pritom žuto ElectroInk procesno bojilo te elektrofotografski tiskarski stroju HP Indigo. Za kolorimetrijsku i slikovnu analizu primjenjena je ECI tiskovna forma koja sadrži 378 definiranih polja. Dobiveni rezultati statistički su obrađeni metodom dvosmjerne analize varijacija. Studija je prikazana pomoću volumena kolornog gamuta, te površinske pokrivenost rasterskih elemenata (točkica). U radu je utvrđeno je da na kvalitetu obojenja prvenstveno utječe debljina nanosa žutog bojila, dok je utjecaj koncentracije žutih pigmenata minoran. Povećanje nanosa bojila sa jedanog na dva imalo je mnogo jači učinak od onog koji je realiziran povećanjem sa dva sloja na tri sloja., In liquid toner electrophotography, colour gamut is often diminished in the yellow region leading to problems with photo quality prints. It is known that the concentration of pigment particles in the printing ink and its thickness when applied on a paper substrate decisively influence final print quality. Variation of these two parameters for the yellow process ink was performed by modifying the printing process of the electrophotographic printer HP Indigo S1000. Printed colour patches of ECI test chart were analysed colorimetrically and using image analysis approach. Two-way analysis of variance was implemented to statistically assess the obtained results. Both studied responses – colour gamut volume and area coverage of halftone dots – were found to be primarily influenced by the yellow ink layer thickness and much less by the ink concentration. Increase from one to two ink layers had a significantly stronger effect on each of the two responses when compared to an additional increase from two to three layers.

U svrhu postizanja boljih svojstava tiskovne je podloge moguće oplemenjivati na različite načine. U ovom radu analizira se mogućnost oplemenjivanja s različitom površinskom pokrivenošću lakova koji se suše UV zračenjem, pri čemu su korištena tri karakteristična papira (papir za umjetnički tisak gloss, offsetni papir i kalandriran papir). Primijenjene metode su bazirane na mjerenju optičkih svojstava lakom impregnirane površine (obojenje, sjaj i glatkoća), kao i na određivanju fizikalnog svojstva upojnosti. Dvojne osobine papirnih podloga dobivaju se nanosom UV laka koji suši LED svjetlošću. Rezultati istraživanja pokazuju da se kod gloss premazanog papira upojnost smanjuje nanosom UV laka, dok se kod nepremazanih papira (offsetni, kalandrirani) upojnost povećava. Nanos laka s manjom površinskom pokrivenošću (33 % UV laka) nije relevantntna za upojnost i optička svojstva naravnih papira. Značajne promjene u hrapavosti i optičkim svojstava postižu se 66 % nanosom, što je posebice vidljivo kod papira za umjetnički tisak., In order to achieve better properties of the printing substrates their improving is possible in various ways. In this article the possibility of the substrate improving is analyzed with different surface coverage of varnishes cured by UV radiation, where three characteristic kinds of paper were used (fine art glossy paper, offset paper and calendered paper). The applied methods are based on measuring the optical properties with the varnish impregnated surface (colouring, gloss, smoothness), as well as determining the physical property of absorbency. Double properties of the printing substrates are obtained by the layer of UV varnish which is cured by LED light. The investigation results show that the absorbency decreases on gloss coated paper by the application of UV varnish coating, while it increases on uncoated paper (offset and calendered paper). The varnish coating with smaller coverage (33 % UV varnish) is not relevant for the absorbency and for optical properties of the natural paper. Important changes in roughness and optical properties are achieved with 66 % coating which is especially visible on fine art paper.