Understanding Color Associations and Their Effects on Expectations of Drugs' Efficacies.

Colors influence our daily perceptions and expectations that manifest in a variety of ways. This research has three main objectives: to demonstrate the relationship between the colors of pills and their expected efficacies, to test this effect on a wide variety of demographics, thereby demonstrating their influence on choices made by participants. Finally, to understand the reasoning behind the choices made by participants, and the color associations exhibited. The results of a series of surveys showed clear similarities and differences across various demographics. The strongest and most consistent color associations were those of white with pain relief and red with stimulant efficacies. The color associations found were red with aggression and power, blue with calmness and serenity, white with calm and purity, yellow with energy, and green with environment and health. The findings of this study can help pharmaceutical companies, and medical practitioners, to better make, market, and prescribe pills, depending on the geographical location, ethnicity, and age group of the patient. This may also strengthen the perceived effects of the pills on patients overall by increasing their compliance rates.

Color appearance shift in augmented reality metameric matching.

The physical additivity of optical-see-through (OST) augmented reality (AR), where display and the real-world overlay with each other, impacts its color appearance. We explored this unique dynamic by looking at the effect of background correlated color temperature (CCT) on AR color appearance with a color matching experiment between a prototype OST-AR RGB system and daylight spectrum reproduction. Different background CCT, luminance levels, and two stimulus types [simulated two-dimensional (2D) disk and three-dimensional (3D) cube] were examined. We found that when the background color is inconsistent with the stimulus providing conflicted cues, matched colors in AR shifted towards the background. The luminance matched on the 3D cube is higher than the 2D disk, suggesting the impact of context on the AR appearance. A controlled metameric matching group between daylight reproduction and LCD or CRT did not show the shift, indicating that the appearance shift is not due to the RGB-spectrum metameric matching, but due to RGB foreground-spectral background interaction beyond simple additivity. How perceptual weighting on the foreground and background is modified to predict the appearance as a function of additivity is discussed.

Brightness matching in optical see-through augmented reality.

A visual experiment using a beam-splitter-based optical see-through augmented reality (OST-AR) setup tested the effect of the size and alignment of AR overlays with a brightness-matching task using physical cubes. Results indicate that more luminance is required when AR overlays are oversized with respect to the cubes, showing that observers discount the AR overlay to a greater extent when it is more obviously a transparent layer. This is not explained by conventional color appearance modeling but supports an AR-specific model based on foreground-background discounting. The findings and model will help determine parameters for creating convincing AR manipulation of real-world objects.

Observer metamerism in commercial displays.

Two uniform patches presented on two displays under identical viewing conditions can appear as the same color to one observer but as mismatched colors to another observer. This phenomenon, called observer metamerism (OM), occurs due to individual differences in color matching functions. To avoid its potentially adverse impacts in display calibration and characterization, it is desirable to have a predictive model of OM. In this work, we report the computational results of how to use existing metrics to quantify the potential OM between commercial display pairs and a proposed OM metric that is verified through a psychophysical experiment.

Assessing the temporal uniformity of CIELAB hue angle.

In recent work [J. Opt. Soc. Am. A36, 1022 (2019)JOAOD60740-323210.1364/JOSAA.36.001022], we found that $\Delta {E^*_\textit{ab}}/{\rm s}$ΔEab∗/s in CIELAB is not suitable for describing the perceived speed of temporal color changes in full-room illumination. Two hue transitions with the same physical speed of change, in terms of $\Delta {E^*_\textit{ab}}/{\rm s}$ΔEab∗/s, were not perceived to change at the same speed. This is not really surprising, since CIELAB was not designed to characterize the perception of temporal color transitions in illumination. In this study, we further investigate the temporal uniformity of CIELAB. The stimuli were presented in a square of 4.3° visual angle surrounded by a 4000 K adapting field, similar to the viewing condition for which CIELAB was designed (i.e., where color stimuli are presented on-axis surrounded by a static adaptation field). The human observers viewed pairs of temporal color transitions which were presented sequentially, and were asked to select the one that appeared to change faster. The results confirmed that under these conditions CIELAB was also not temporally uniform. We present preliminary attempts to improve the temporal uniformity for both CIELAB and cone-excitation spaces (i.e., LMS and DKL (Derrington-Krauskopf-Lennie [J. Physiol.357, 241 (1984)JPHYA70022-375110.1113/jphysiol.1984.sp015499]).

Perceived speed of changing color in chroma and hue directions in CIELAB.

In dynamic LED lighting, the perceived speed of changing color is an important concept; however, there exists no suitable temporal color space. In a psychophysical experiment, we compared the perceived speed of periodic temporal transitions in CIELAB chroma and hue directions around five base colors [the five Munsell hues: 5R (red), 5Y (yellow), 5G (green), 5B (blue), and 5P (purple)]. The experiment was conducted in a light laboratory, with the main illumination stimulus subtending a visual angle of 101×77 deg. In sequential paired presentations, observers were asked to identify which transition appeared faster, and points of subjective equality between transitions were computed. The speed of transitions was defined in CIELAB ΔEab*/s, which was shown to be temporally non-uniform; uniformity was improved using a modified color space based on speeds in the DKL space of Derrington et al. [J. Physiol.357(1), 241 (1984)].

Characterization and control of a multi-primary LED light lab.

A new light lab facility has been commissioned at Rochester Institute of Technology with the research goal of studying human visual adaptation under temporally dynamic lighting. The lab uses five-channel LED luminaires with 16 bits of addressable depth per channel, addressed via DMX. Based on spectral measurements, a very accurate multi-primary additive color model has been built that can be used to provide "colorimetric plus" multi-primary channel intensity solutions optimized for spectral accuracy, color fidelity, color gamut, or other attributes. Several spectral tuning and multi-primary solutions are compared, for which accuracy results and IES TM-30-15 color rendition measures are shown.

Veiling glare and perceived black in high dynamic range displays.

A perceptual experiment was conducted to measure the visibility of black-level differences in the proximity of a bright glare source. In a controlled viewing environment, visual difference thresholds were adaptively measured using dark, shadow-detail images shown on a high dynamic range liquid crystal display while an external LED lamp was used to induce intra-ocular glare over a small range of eccentricities. This high-contrast situation is relevant to high dynamic range displays that may have bright regions in displayed images, as well as to viewing environments that include lamps or other light sources. The resulting difference thresholds are modeled with a combination of the CIE total glare equation, the DICOM contrast visibility model, and a new estimate of adaptation luminance.