Förslaget inkom 2007-01-31
The influence of mean gloss level on perceived whiteness
OBS! ANSÖKNINGSTIDEN FÖR DETTA EXJOBB HAR LÖPT UT.
The primary function of printed paper products is to visually communicate impressions and information using images and text. The perception of the overall quality of a print depends on its interaction with the illumination and the observer. The optical properties of printed paper are mainly related to the light scattering and absorption processes in the ink and the paper but the perception of print quality depends to a large extent on the observer. One important property of paper is its perceived whiteness, an attribute of colours of high luminous reflectance and low purity. Extensive research on the perception of whiteness has shown that observers are able to arrange white samples of different luminous reflectance, hue, and saturation in a one-dimensional order according to whiteness, although little general agreement between observers on whiteness can be reached. The general agreement is that a sample is perceived as all the whiter, the lighter, and the bluer (to some extent) it is. Many evaluation methods and whiteness formulae have been proposed over the years to develop instrumental measurements that correlate with the perception of whiteness of human observers. However none of them are taking the effect of the surrounding colour or surface properties such as gloss into account.
STFI-Packforsk is conducting a 3-year project together with participating companies from the paper industry to study these effects and incorporate them into a more general whiteness model. The objective of this Master's thesis is to focus on the influence of the mean surface gloss of a sample on its perceived whiteness. The work includes defining, producing and optically characterising a set of appropriate samples, conduct and analyse psychophysical experiments with panels of judges, and finally propose ways to take the mean gloss into account in instrumental whiteness determination. Depending on the progress of the thesis a method for producing samples of defined instrumental whiteness will also be developed.