Spectral color reproduction minimizing spectral and perceptual color differences

Abstract

In this article, we are combining minimization criteria in the colorant separation process for spectral color reproduction. The colorant separation is performed by inverting a spectral printer model: the spectral Yule-Nielsen modified Neugebauer model. The inversion of the spectral printer model is an optimization operation in which a criterion is minimized an each iteration. The approach we proposed minimizes a criterion defined by the weighted sum of a spectral difference and a perceptual color difference. The weights can be tuned with a parameter alpha epsilon [0, 1]. Our goal is to decrease the spectral difference between the original data and its reproduction and also to consider perceptual color difference under different illuminant conditions. In order to find the best alpha value, we initially compare a pure colorimetric criterion and a pure spectral criterion for the reproduction, then we combine them. We perform four colorant separations: the first separation will minimize the 1976 CIELAB color difference where four illuminants are tested, the second separation will minimize an equally weighted summation of 1976 CIELAB color difference with the four illuminants tested independently, the third colorant separation will minimize a spectral difference, and the fourth colorant separation will combine a weighted sum of a spectral difference and one of the two first colorimetric differences previously introduced. This last colorant separation can be tuned with a parameter in order to emphasize on spectral or colorimetric difference. We use a six colorants printer with artificial inks for our experiments. The prints are simulated by the spectral Yule-Nielsen modified Neugebauer model. Two groups of data are used for our experiments. The first group describes the data printed by our printing system, which is represented by a regular grid in colorant space of the printer and the second group describes the data which is not originally produced by our printing system but mapped to the spectral printer gamut. The Esser test chart and Macbeth Color Checker test chart have been selected for the second group. Spectral gamut mapping of this data is carried out before performing colorant separation. Our results show improvement for the colorant separations combining a sum of 1976 CIELAB color difference for a set of illuminants and for the colorant separation combining a sum of 1976 CIELAB color difference and spectral difference, especially in the case of spectral data originally produced by the printer

Colour Image Reproduction for 3D Printing Facial Prostheses

“…This primarily involves colour management of the 2D colour image from the camera RGB to printer RGB for each pixel using specific camera and printer colour profiles respectively. For this specific task, the colour profiles used were developed using both conventional colorimetric and spectral-based reproduction methods [19,20]. When the colour management is finalised, surface texture mapping is conducted to map the newly generated colour image onto the manipulated 3D model.…”

Simple Comparison of Spectral Color Reproduction Workflows

“…In this article the n factor has been set to n = 2. As opposed to the inversion of the YNSN model by optimization we do not use the Demichel [10] equations in our gamut mapping operation [4]. The gamut mapped spectral reflectances are displayed in Figure 4 (b).…”

“…we want to reduce the metamerism. This task is performed by inverting the spectral Yule-Nielsen modified Neugebauer printer model [4], [5], [6].…”

Channel selection for multispectral color imaging using binary differential evolution

“…When the imaging system has been calibrated and characterized, the spectral reflectance data of the imaged sample can be obtained at pixel-level resolution [2,3]. Because of its advantages, multispectral color imaging has been widely applied in various areas such as scene simulation [4], digital archiving [5], and spectral color measurement [2,6].…”