Perceived Differences of Lightness Deviation during the Appearance of Simultaneous Contrast Effect in Printing Process

This paper shows the research data of psychophysical visual effect of simultaneous contrast when changing RTV of background lightness in the printing process. An experimental research on graphic reproductions made in the offset printing technique with specifically constructed design solutions that cause the above mentioned effect was carried out. Samples were designed as ten various lightness variances of background, with a range from 10% RTV to 100% RTV, on which there are primary stimuli with value of 50% RTV. The visual experiment was performed by using simultaneous binocular harmonization technique, and it involved 20 respondents. The respondents were tasked with harmonizing the primary stimuli from the test reproduction in relation to the referential one, so that they were to be perceived as equal on both reproductions. For statistical data processing, one-way repeated measurements ANOVA was used, which found statistically consequential differences among means of deviations in perceived lightness of primary stimuli. Post-hoc analysis by Fisher shows pairs that are reciprocally different (p < 0,05). The obtained results clearly indicate the regularities of the appearance of simultaneous contrast effect on printed medium, all with the aim of creating a model for predicting it and finding a conceptual design solution in which the effect is pronounced the least