Immersive technologies offer new approaches for engaging audiences and providing visual information, whether for entertainment or more practical applications. To ensure that the content maintains the intended appearance across different devices and environments, one of the key challenges is accurate color management. In this paper, we discuss the challenges that have to be overcome to create color-accurate immersive experiences at a cinematic quality level. We propose workflows for efficiently characterizing different virtual and augmented reality devices and review their color reproduction capabilities against current display standards.

Virtual reality offers a new way of telling stories and engaging audiences. To create appealing content for this new imaging modality, content production and post-production workflows need to be adapted or completely rethought. One key aspect for ensuring image quality and preservation of the director's intent throughout the production workflow is color management. In this paper, we review color managed workflows for (post) production and explore the challenges that arise for ensuring color accuracy in VR. We focus on the display end of the imaging pipeline, presenting a workflow for characterizing and calibrating VR devices. Our workflow is evaluated on several key VR devices, allowing us to compare their display characteristics and calibration quality.

Human color vision differs from person to person, not only when color deficiencies occur but also within color-normal populations. Investigating individual variability in normal color vision is beneficial both for clinical purposes and for quantifying observer metamerism. Researchers have used color matches such as Rayleigh matches, Moreland matches, the D&H color rule, and various combinations of different media for such investigations. However, none of them were originally aimed at investigating the interobserver variability in color-normal populations, but rather were aimed at screening for color-deficiencies. The objective of this study was, therefore, to design and carry out a color matching experiment where observer variability appeared as large as possible to detect the interobserver differences in the color-normal population. Color matching was simulated under different combinations of reference spectrum and matching primaries using ColorChecker patches, different display/projector primaries, and the Stiles and Burch 49 observers. The simulation results showed: (1) The choice of spectra for the matching primaries had a significant effect on observer variability, (2) observer variability was large for near-neutral reference colors, and (3) observer variability in the lightness direction was small relative to chromatic variability. The color matching experiment highlighting interobserver variability was designed based on these three findings and carried out for 61 color-normal observers. Typical interobserver variability was 9.2 mean color difference from the mean (MCDM) using CIEDE2000 (spanning about 40 CIELAB units), which was much larger than any previous experiment. The obtained color matching data are useful for derivation, validation, and analysis of color matching functions. (C) 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 530-539, 2016; Published Online 23 June 2015 in Wiley Online Library (wileyonlinelibrary.com).

Wide color gamut media are emerging in the market, and this trend has been accelerated by ITU recommendation, Rec.2020 in 2012. Wide color gamut media possess spectrally narrow primaries, which would potentially increase the degree of observer metamerism. In this study, it was investigated if observer metamerism could be a serious issue under practical viewing conditions. Namely, real images were used as a matching stimulus instead of uniform colors. We carried out the color image matching experiment on two different media: an Apple Cinema HD LCD monitor and a Microvision laser projector. The results from 28 color-normal observers were analyzed. The obtained inter-observer variability was large enough that observer metamerism would be a serious issue where the laser projector is viewed together with conventional media. Each observer had a match point that was significantly different from those of other observers. It was found that effective field size changes (and an observers CMFs change) depending on image contents. Complex images require smaller field size whereas simple images require larger field size.

A color matching experiment was designed and carried out to estimate human observers' color matching functions (CMFs). 61 color-normal observers participated in the experiment. Their results were traced back to physiological factors using a mathematical vision model. The experiment time was 15 minutes, which is much faster than previous research aimed at determining color matching functions.

Recent display technologies (LCD backlight, OLED) allow watching images with more contrast and more saturated colors than even digital cinema. Unfortunately, today's video content and broadcast cannot convey such colors due to the currently used colorimetry standard (ITU-R.BT 709). Solutions exist for more contrast and wider color gamut, but they are different in the video and photography worlds. New standardization initiatives for video (IEC 61966-2-4, ITU-R) try to set up a new, extended but fixed colorimetry, while digital photography applies - since a decade – flexible color management (ICC). However, in all these approaches the color gamut of either devices or contents is not described explicitly. This paper presents the new international standard IEC 61966-12-1 “Metadata for identification of colour gamut (Gamut ID)”. This standard allows the precise and flexible description of a color gamut. The metadata supports graphics hardware, scalability, memory footprint efficiency, convex handling of non-convex gamuts, handling of fuzzy color gamuts, and handling of gamut cusps. This standard may be used in future systems for video color management or for image-dependent gamut mapping.

In this paper we investigate the impact of colorimetric observer categories on the prediction of the average suprathreshold color difference perception. The observer categories were obtained from an observer classification experiment, while the color difference data were obtained from an experiment involving a liquid crystal display (LCD) with fluorescent backlight. The same observer panel with normal color vision participated in both experiments. Results obtained from the observer classification experiment were consistent with the average observer threshold for color difference judgment. This analysis demonstrates that the observer categories, determined based on individual differences in cone spectral sensitivities (and thus color matching functions), have an influence on the prediction of average suprathreshold color difference perception for a given observer population.

The variability among human observers is a challenge to the calibration of modern displays based on Light Emitting Diodes (LED) and lasers. The spectra of the displayed colors are so peaky that slight differences in the cone sensitivities in human color vision are sufficient to make two observers perceiving different colors on the same screen. Recently published results give evidence to the existence of a small number of classes of human observers. In this paper, we present first results on the development of a prototype for a lightweight, inexpensive, temporally stable and easy to calibrate and easy to use instrument that allows classification of an observer with normal color vision in a small number of categories. The instrument employs a set of LEDs having specific wavelengths and is controlled by a computer interface. The use of such an instrument will allow adapting displays and viewing conditions to individual observers in color-critical applications.

Various recent studies have shown that observer variability can be a significant issue in modern display colorimetry, since narrow-band primaries are often used to achieve wider color gamuts. As far as industrial applications are concerned, past works on various aspects of observer variability and metamerism have mostly focused on cross-media color matching, an application context that is different from color matching on two displays, both in terms of human visual performance and the application requirements. In this paper, we report a set of three preliminary color matching experiments using a studio Cathode Ray Tube (CRT) display with broadband primaries, and a modern wide-color gamut Liquid Crystal Display (LCD) with narrow-band primaries, with and without surround. Two principal goals of these pilot tests are to validate the experimental protocol, and to obtain a first set of metameric data of display color matches under different viewing conditions. In this paper, various experimental design considerations leading to the current test setup are discussed, and the results from the pilot tests are presented. We confirm the validity of our test setup, and show that the average color matches predicted by the 1964 CIE 10° standard observer, although acceptable as average matches, can often be significantly and unacceptably different from individual observer color matches. The mean, maximum and the 90th percentile values of the standard observer-predicted color difference of individual observer color matches were 1.4, 3.3 and 2.6 ΔE*00 respectively.

The variability among color-normal observers poses a challenge to modern display colorimetry because of their peaky primaries. But such devices also hold the key to a future solution to this issue. In this paper, we present a method for deriving seven distinct colorimetric observer categories, and also a method for classifying individual observers as belonging to one of these seven categories. Five representative L, M and S cone fundamentals (a total of 125 combinations) were derived through a cluster analysis on the combined set of 47-observer data from 1959 Stiles-Burch study, and 61 color matching functions derived from the CIE 2006 model corresponding to 20-80 age parameter range. From these, a reduced set of seven representative observers were derived through an iterative algorithm, using several predefined criteria on perceptual color differences (delta E*00) with respect to actual color matching functions of the 47 Stiles-Burch observers, computed for the 240 Colorchecker samples viewed under D65 illumination. Next, an observer classification method was implemented using two displays, one with broad-band primaries and the other with narrow-band primaries. In paired presentations on the two displays, eight color-matches corresponding to the CIE 10° standard observer and the seven observer categories were shown in random sequences. Thirty observers evaluated all eight versions of fifteen test colors. For majority of the observers, only one or two categories consistently produced either acceptable or satisfactory matches for all colors. The CIE 10° standard observer was never selected as the most preferred category for any observer, and for six observers, it was rejected as an unacceptable match for more than 50% of the test colors. The results show that it is possible to effectively classify real, color-normal observers into a small number of categories, which in certain application contexts, can produce perceptibly better color matches for many observers compared to the matches predicted by the CIE 10° standard observer.

New technologies in capturing and displaying images with extended color gamut and new standards for wide color gamut color encoding enable a new market of extended-color-gamut content (cinema, television, video on demand, games, electronic documents). This paper addresses the scenario of introducing extended-color-gamut motion picture production, postproduction and distribution. One technical issue is the management and compatibility of different color gamuts. Manual (high-end) and automatic (consumer) color conversion tools are needed. For this purpose, we analyze in this paper different gamut mapping algorithms for motion picture type content. A psycho-physical evaluation framework is developed that is based on motion-picture related quality criteria aiming the preservation of the artistic intent and the optimal use of destination color gamut. We notably focus on gamut mapping algorithms that analyze geometrically both the source and the destination color gamut. A new method for automatic detection of the cusp of a color gamut is developed and used for cusp to cusp gamut mapping. The evaluation of several gamut mapping algorithms shows that best results are obtained for cusp to cusp mapping. According to the motion picture evaluation framework, the cusp to cusp gamut mapping algorithm performs significantly better, notably for night scenes and animated content.