In this work, we have focused on analyzing how different variables affect in the process of detecting the sparkle texture effect, since there are few works related to this issue. A large number of samples were available with different characteristics depending on the needs of each psychophysical experiment. The studied parameters were structural variables such as pigment type, size and concentration, and environmental variables such as illumination and viewing conditions. Due to the large sample number, the design of experiments (DoE) was applied to optimize the psychophysical experiments and to evaluate which variables affect individually on the sparkle detection, as well as if there are interactions among them. After collecting all the information from the psychophysical experiments, with more than 35.000 visual assessments performed, the correlation with the instrumental data of the BYK-mac was verified to corroborate its reliability. It has been possible to demonstrate the influence of multiscale parameters on the sparkle appearance and to extract which variables affect to a greater extent when detecting the sparkle texture effect. This issue was fundamental because, there was no previous study addressing these issues, which was of vital importance for the industry to analyze how the sample texture is detected depending on various conditions, whether structural, environmental, etc. In addition, a reliable and applicable methodology has been implemented for other types of existing goniochromatic pigments with novel texture effects. It has been possible to implement the design of experiments as a main tool to limit the visual experiments to be performed, making the fewest visual evaluations possible and obtaining the maximum results. Thanks to psychophysical experiments, it has been successfully tested the visual and instrumental correlation of sparkle detection between the only multi-angle device on the market to date, and the visual assessments obtained from a large number of observers.
Omar Gómez, Esther Perales, Bàrbara Micó, Valentín Viqueira, Khalil Hurabait, Francisco M. Martínez-Verdú, "Statistical design of experiments applied on sparkle visual detection" in Proc. IS&T 25th Color and Imaging Conf., 2017, pp 296 - 301, https://doi.org/10.2352/ISSN.2169-2629.2017.25.296