Various parameters and observation conditions contribute to the emergence of color. This phenomenon poses a challenge in modern visual communication systems, which are continuously being enhanced through new insights gained from research into specific psychophysical effects. One such effect is the psychophysical phenomenon of simultaneous contrast. Nearly 90 years ago, Kurt Koffka described one of the earliest illusions related to simultaneous contrast. This study examined the perception of gray tone variations in the Koffka ring against different background color combinations (red, blue, green) displayed on a computer screen. The intensity of the effect was measured using lightness difference ΔL₀₀ across light-, medium-, and dark-gray tones. The results were analyzed using descriptive statistics, while statistically significant differences were determined using the Friedman ANOVA and post hoc Wilcox tests. The strongest visual effect was observed the for dark-gray tones of the Koffka ring on blue/green and red/green backgrounds, indicating that perceptual organization and spatial parameters influence the illusion’s magnitude. The findings suggest important implications for digital media design, where understanding these effects can help avoid unintended color tone distortions caused by simultaneous contrast.

In the achromatic White's grid, the grey patches between the grey lines are perceived as darker while the same elements inserted between white lines are perceived lighter than their true measured values. A number of authors attempted to calculate the magnitude and direction of this effect using mathematical models based on multiple spatial filters. This paper uses different mathematical model, based on regression analysis, which has shown itself as an excellent tool for prediction of direction and magnitude of White's effect. The psychophysical visual experiment was conducted on 38 subjects of both genders. The differences in lightness perception ∆L00 were calculated in CIE ∆E_2000 system. This paper determined the functional dependence of White's effect magnitude ∆L00 to the lightness L of rectangular elements in White's achromatic grid. The results gave the square polynomial of very high quality (R2 = 0,974). Regression polynomials were also found. The gave numerical values ∆L00 of difference in perception of left and right elements in comparison to their physical values (left R2 = 0,943, right R2 = 0,938) in dependence to variation of lightness parameter L. Results of the research clearly show the mathematical pattern of White's effect based on the lightness of rectangular elements.

Attracting and retaining the attention of users, or motivating them to use the particular product being the main task of designers in graphic design for all materials, from printed to digital media. It is crucial to select colors that are more appealing to the target audience. The aim of this paper is to explore the differences in color preferences depending on age groups in a nationally representative sample of the Republic of Croatia consisting of 1,000 research participants. For this purpose, a questionnaire was created to collect information on the color preferences of participants, and as a result of this research, it was determined that there are statistically significant differences in the preferences for certain colors depending on the age groups of the participants. It has also been shown that there are both increasing and stable or decreasing trends in color preferences depending on age groups.

This paper examines how different background color combinations influence the perception of grey tones in primary stimuli within modified Koffka ring configurations displayed on a computer screen. A custom software application was used with 60 observers, who adjusted perceived grey tones for three primary lightness levels (dark, medium, light) across 27 test samples combining three Koffka ring variants and chromatic backgrounds (red, blue, green). The strength of the simultaneous contrast effect was quantified using the color appearance difference ΔE₀₀, while accompanying shifts in chroma (ΔC) and hue (ΔH) were also evaluated and analyzed by descriptive statistics, Friedman ANOVA, and post hoc Wilcoxon signed-rank tests. The results show that the effect is strongest for dark-grey tones and clearly visible on blue–green and red–green backgrounds, moderate on red–blue backgrounds, and weak or negligible for light-grey tones, with ΔC and ΔH remaining very small, indicating a predominantly lightness-based illusion. These findings provide guidance for digital media design by indicating which combinations of grey levels, spatial configurations, and background colors are most likely to produce unwanted simultaneous contrast in screen-based applications.