# Print Quality Analysis of Stone Paper and Coated Sticker Paper Used in Screen Printing
## 3 Methods  
### The CIE Color Values and Delta E (\(\Delta\)E)  
Color measurements were conducted using an X-Rite spectrophotometer, which operates within a spectral range of 380-780 nm, utilizes a D50 filter, and features a 2\({}^{\circ}\) measurement geometry and a 4.5 mm aperture diameter. The L*a*b* color values of the printed materials were measured, and their Total Color Difference (\(\Delta\)E) was assessed in comparison to the benchmark values specified by the ISO 12647-5 (2015) [48] standard for screen printing. The 12647 series prepared by ISO generally concerns printing processes' standardization and quality control. The ISO 12647-5 (2015) standard is specifically related to screen printing.  
In the L*a*b* color space, L* signifies lightness, extending from 100 (denoting white) to 0 (representing black). Concurrently, the a* and b* components articulate chromaticity, defined as the attribute of a color distinct from its luminance. Notably, a* and b* represent color orientations: -a* aligns with the green axis and +a* with the red axis, whereas -b* corresponds to the blue axis and +b* to the yellow for the stone paper axis [49].  
\(\Delta\)E reveals the difference between the displayed and original colors [50]. Specifically, the \(\Delta\)E\({}_{00}\) formula includes special terms that enhance the performance of interactions between color tones, particularly improving the performance of blue and gray colors [51]. Lower \(\Delta\)E values indicate high accuracy between the colors, while higher \(\Delta\)E values indicate an inconsistency between the colors. \(\Delta\)E values range between 0 and 100; values of < 1 indicate a color difference that cannot be perceived by the human eye, between 1 and 2 indicate a color difference that can be perceived upon close observation; between 2 and 10 indicate an acceptable color difference at a glance, between 11 and 49 indicate a significant color difference, and a value of 100 indicates opposite colors. Keeping constant the CIE L*a*b* color values, the color difference value (\(\Delta\)E\({}_{00}\)) of other links was calculated using Equation (1).  
\[\Delta\)E\({}_{00}=\sqrt{\bigg{(}\frac{\Delta\Gamma^{\prime}}{k_{L}S_{L}}\bigg{)}^{2}+ \bigg{(}\frac{\Delta\Gamma^{\prime}}{K_{C}S_{C}}\bigg{)}^{2}+\bigg{(}\frac{ \Delta H^{\prime}}{K_{H}S_{H}}\bigg{)}^{2}+R_{T}\bigg{(}\frac{\Delta\Gamma^{ \prime}}{K_{C}S_{C}}\bigg{)}\bigg{(}\frac{\Delta H^{\prime}}{K_{H}S_{H}}\bigg{)}} \tag{1}\]  
where R\({}_{T}\) is the hue rotation term, K\({}_{L}\), K\({}_{C}\), and K\({}_{H}\) are parametric factors, L, C, and H represent compensation for neutral colors, S\({}_{L}\) is compensation for lightness, S\({}_{C}\) is compensation for chroma, and S\({}_{H}\) is compensation for hue [52; 53; 54; 22].  
In the ISO 12647-5 (2015) standard for screen printing, three distinct color gamuts for CMYK (cyan, magenta, yellow, and black) ink sets are specified as small, medium, and large. The large gamut L*a*b* references indicate more saturated color values than small and medium gamuts within the same standard. For instance, the medium gamut cyan color value in ISO 12647-5 (2015) is provided as L: 52, a: \(-\)33, b: \(-\)51, and the large gamut cyan color value is L: 46, a: \(-\)32, b: \(-\)54, demonstrating the higher saturation of the large gamut [49; 55].