Ludovic Gustafsson Coppel

Abstract
The effect of mean gloss level on perceived whiteness was evaluated by magnitude estimation and pair wise comparison of papers with varying shades and gloss levels. The samples were printed on substrates of different gloss to target L*a*b* values measured under a light booth illumination having a 5000 K correlated colour temperature. Observers were able to rate the whiteness of the samples with large mean gloss differences in the 5000 K illumination and in the same illumination with an additional UV lamp. The CIE whiteness equation predicted well the perceived whiteness in both illuminations and the mean gloss level had no significant effect on perceived whiteness. This means that the CIE whiteness equation can be used to compare the perceived whiteness of papers having very different mean gloss levels. However, due to the different amount of fluorescent whiteness agents (FWA) in the papers, the perceived whiteness prediction was only valid when the measurement was performed under the same illumination as for the visual evaluations. Typical indoor illumination with florescent light tubes contains much less UV than the D50 or C illuminants. The instrumental whiteness differences due to mean gloss and instrument geometry were negligible compared to the effect of the UV content of the illumination.

Keywords: Whiteness, Gloss, Perception, Fluorescence
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Janne Laine

Abstract
Psychometric experiments were carried out in order to increase the understanding of how special effects influence the consumer perception of printed products. Seven different contents ranging from advertisements to covers of packages and annual reports were chosen and different special effect versions of each were created. The following types of special effects were used: metallic inks, selective gloss or pearlescent varnishing, and scented varnish. Conventional CMYK samples without special effects were also included in the sample set for reference. A total of 49 observers participated in the subjective assessment of the special effect print samples. An assessment session with a single observer consisted of a number of different assessment tasks and lasted for approximately 1.5 hours. Especially the gloss and pearlescent varnish effects were seen to increase the effectiveness of a printed product in attracting the viewers’ attention, compared to samples with no special effects. In some cases a significant improvement in the preference assessments was also achieved with the use special effects, particularly the two varnish effects mentioned above. Principal component analysis (PCA) was applied to distil from the large data set of subjective assessments (50 attributes of 12 print samples assessed by 49 observers, for a total of 29400 observations) the essential perceptual shifts caused by the printed special effects. The first two principal components explained the majority of perceived differences between the special effect print samples, and were interpreted to correspond to perceptual dimensions that were termed Noteworthiness and Aesthetic Value.

Keywords: Special effects, Printing, Perception, User experience, Psychometry
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Siv Lindberg, Annika Lindström

Abstract
This study investigates the perception of print quality in printed images using eye movement recordings and psychophysical scaling. Further, the relation between the perceptual criteria: print quality, colour accuracy, sharpness, and print mottle are investigated. Eye-movement patterns were compared during evaluation. Results show that although average perceptual scales show a good agreement between experts and laymen, eye-tracking data show that different visual strategies are adopted in certain cases. In particular, experts have significantly fewer fixation counts and longer average fixation duration during all assessment criteria, compared to laymen. This may indicate that experts have a more focused way of evaluating print quality criteria, that they have a strategy about where to look in an image when assessing a specific criterion.

Keywords: Print quality Eye-tracking Colour accuracy, Sharpness
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