Parametric effects on the evaluation of threshold chromaticity differences using red printed samples

Abstract

510 517 36 4 ; S ; This paper was published in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: https://doi.org/10.1364/JOSAA.36.000510. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. [EN] Results from different authors showed deviations of radial orientation in the a*-b* plane (tilt) for the major axes of chromaticity-discrimination ellipses centered around the International Commission on Illumination (CIE) red color center [Color Res. Appl. 3, 149 (1978)], which are not considered by most of the current advanced color-difference formulas (e.g., CIEDE2000). We performed a visual experiment using red printed samples in order to test the influence of the separation between samples (gap) on the mentioned tilt. Our results confirm a counterclockwise tilt of fitted a*-b* ellipses with a magnitude of approximately 36 degrees for samples with no separation, which is similar to that detected by other authors, and a reduction of the mentioned tilt owing to the separation of the samples. We detected a tilt of approximately 22 degrees for samples with a black gap of 0.5 mm and a tilt of approximately 25 degrees for samples with a white gap of 3 mm. Notably, the uncertainty of previous values given by the corresponding credibility intervals of 95% posterior probability is approximately +/- 8 degrees of the mean values. Finally, we study the performance of the most widely used color-difference formulas in the graphic arts sector using our current experimental results, and conclude that the performance of the CAM02-SCD and CAM02-UCS color-difference formulas is significantly better than that of the CIEDE2000 formula. Brusola Simón, F.; Tortajada Montañana, I.; Jorda-Albiñana, B.; Melgosa, M. (2019). Parametric effects on the evaluation of threshold ...