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.

Polymer waste poses significant environmental challenges and polymers’ replacement with biodegradable biopolymers is therefore crucial. Protective coatings are recognized as a problem in the graphics industry, since they are based on synthetic polymers that are not biodegradable. To be effective, coatings in this industry must meet several key criteria, including stability, functionality, recyclability, and a suitable shelf life. One potential alternative is starch, a highly abundant biopolymer that has been researched for its application in coating preparation. However, its poor mechanical properties have limited its use in this area. This paper investigates the functional properties of starch-based biopolymer coatings enhanced with D-sorbitol and bioactive components: trans-ferulic and L-ascorbic acid. The impact of these additions on the mechanical stability and UV protection potential of the coatings was evaluated. Thermochromic pigments are highly sensitive to UV radiation, making them a useful indicator for evaluating the UV protection factor of a given coating. The colour change of the coated thermochromic prints after UV irradiation was quantitatively evaluated using spectrophotometric analysis. Mechanical properties were assessed through tensile strength, elongation at break, burst strength, and folding endurance. Overall, coatings increased burst strength and improved key mechanical properties depending on the additive combination.