Spectrally Based Material Color Equivalency: Modeling and Manipulation

A spectrally based normalization methodology (Wpt normalization) for linearly transforming cone excitations or sensor values (sensor excitations) to a representation that preserves the perceptive concepts of lightness, chroma and hue is proposed resulting in a color space with the axes labeled W , p, t. Wpt (pronounced “Waypoint ) has been demonstrated to be an effective material color equivalency space that provides the basis for defining Material Adjustment Transforms that predict the changes in sensor excitations of material spectral reflectance colors due to variations in observer or illuminant. This is contrasted with Chromatic Adaptation Transforms that predict color appearance as defined by corresponding color experiments. Material color equivalency as provided by Wpt and Wpt normalization forms the underlying foundation of this doctoral research. A perceptually uniform material color equivalency space (“Waypoint Lab or WLab) was developed that represents a non-linear transformation of Wpt coordinates, and Euclidean WLab distances were found to not be statistically different from ∆E⋆94 and ∆E00 color differences. Sets of Wpt coordinates for variations in reflectance, illumination, or observers were used to form the basis of defining Wpt shift manifolds. WLab distances of corresponding points within or between these manifolds were utilized to define metrics for color inconstancy, metamerism, observer rendering, illuminant rendering, and differences in observing conditions. Spectral estimation and manipulation strategies are presented that preserve various aspects of “Wpt shift potential as represented by changes in Wpt shift manifolds. Two methods were explored for estimating Wpt normalization matrices based upon direct utilization of sensor excitations, and the use of a Wpt based Material Adjustment Transform to convert Cone Fundamentals to ”XYZ-like Color Matching Functions was investigated and contrasted with other methods such as direct regression and prediction of a common color matching primaries. Finally, linear relationships between Wpt and spectral reflectances were utilized to develop approaches for spectral estimation and spectral manipulation within a general spectral reflectance manipulation framework – thus providing the ability to define and achieve “spectrally preferred color rendering objectives. The presented methods of spectral estimation, spectral manipulation, and material adjustment where utilized to: define spectral reflectances for Munsell colors that minimize Wpt shift potential; manipulate spectral reflectances of actual printed characterization data sets to achieve colorimetry of reference printing conditions; and lastly to demonstrate the spectral estimation and manipulation of spectral reflectances using images and spectrally based profiles within an iccMAX color management workflow

Method to determine the degrees of consistency in experimental datasets of perceptual color differences

This paper was published in Journal of the Optical Society of America A 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://www.osapublishing.org/josaa/abstract.cfm?uri=josaa-33-12-2289. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law"We propose a fuzzy method to analyze datasets of perceptual color differences with two main objectives: to detect inconsistencies between couples of color pairs and to assign a degree of consistency to each color pair in a dataset. This method can be thought as the outcome of a previous one developed for a similar purpose [J. Mod. Opt. 56, 1447 (2009)], whose performance is compared with the proposed one. In this work, we present the results achieved using the dataset employed to develop the current CIE/ISO color-difference formula, CIEDE2000, but the method could be applied to any dataset. Specifically, in the mentioned dataset, we find that some couples of color pairs have contradictory information, which can interfere in the successful development of future color-difference formulas as well as in checking the performance of current ones. (C) 2016 Optical Society of AmericaMinisterio de Economia y Competitividad (MINECO) del Gobierno de Espana (FIS2013-40661-P, FIS2013-45952-P, MTM2015-64373-P); European Regional Development Fund (ERDF).Morillas, S.; Gómez-Robledo, L.; Huertas, R.; Melgosa, M. (2016). Method to determine the degrees of consistency in experimental datasets of perceptual color differences. Journal of the Optical Society of America A. 33(12):2289-2296. doi:10.1364/JOSAA.33.002289S22892296331

Color appearance processing using iccMAX

ICC.2:2017 is a revision to the next-generation colour management specification iccMAX that introduces new support for colour appearance processing. iccMAX includes a built-in colour appearance model IccCAM, together with a rich programming environment, and support for spectral data, material channel connections, BRDF and processing elements that make it possible to functionally encode any appearance model. ICC.2:2017 introduces many new capabilities, including the ability to provide environment variables which allow parameters such as image statistics or viewing conditions to be passed to the transform at run-time. ICC.2:2017 supports a wide range of colour appearance computations within the colour management workflow

Understanding Perceptions of Health Risk and Behavioral Responses to Air Pollution in the State of Utah (USA)

Poor air quality in Utah creates an array of economic, environmental, and health-related impacts that merit investigation and informed political responses. Air pollution is known to cause a variety of health problems, ranging from increased rates of asthma to cardiovascular and lung disease. Our research investigates the extent of Utahn’s understanding of the health risks associated with long-term and short-term impacts of air quality. To assess the degree to which Utahn’s perceive the health risks of air pollution, we performed an ordinal logistic regression analysis using responses to the Utah Air Quality Risk and Behavioral Action Survey, a representative panel survey administered between November 2018 and January 2020 (n = 1160), to determine how socioeconomic status impacts risk perception. Socioeconomic status is not a predictor of perceiving air’s short-term risks to health. Those with more conservative political orientation, as well as those with higher religiosity scores, were less likely than those with more liberal political orientation or those with lower religiosity scores to strongly agree that air pollution poses short-term health risks. We find that for short-term health risks from air pollution, Utahns in the middle-income category are more likely than those in the low-income category to strongly agree that air pollution poses long-term health risks. In addition, those with more conservative political orientation were less likely than those with more liberal political orientation to strongly agree that air pollution poses long-term health risks

Spectral estimation of chromatically adapted corresponding colors

This paper reviews the estimation of spectral reflectance for corresponding colors in XYZ color space, including both corresponding color data sets and chromatically adapted colorimetry. For use in color management workflows, the performance of an inverse transform of the chromatically adapted data was evaluated using spectral estimation. These estimated spectra were then evaluated against the estimated spectral reflectances of reference corresponding color data to analyze the similarity. The results show that established methods using PCA can be used to obtain good spectral estimates, and the methods described in this paper can be implemented in a color managed workflow where spectral processing and output are desired