곽영신 교수

The performance of two newly derived LCD-projector characterisation models has been tested for four liquid crystal based displays – two LC projectors and two LC flat panels. Data measured from a series of test colours, indicated that all LC-based displays showed similar characteristics, including an S-shaped tone characteristic curve and poor channel chromaticity constancy. It is proved that the new characterisation models based on a hyperbolic function fit the tone curve very accurately

Color matching experiments were conducted for 11 pairs of displays, using 7 displays with different spectral characteristics. The color matching results between the LCD display and displays that have a narrowband spectrum, such as a laser projector, QLED, or OLED, demonstrated a significant color difference between two matched colors. The maximum difference was 18.52 ΔE 00 , which indicates the white color difference between the LCD and laser projector. There was also a clear observer variabilit

Color characteristics of an RGBW (red, green, blue, white) electrophoretic display (EPD) prototype developed by Samsung Electronics are analyzed. EPD shows strong crosstalk between subpixels because of both the fringe field between subpixels and the scattering phenomena at the display surface. An RGB-to-RGBW color-decomposition algorithm optimized to EPD characteristics is developed that compensates for color deterioration due to the fringe field and scattering phenomena. For the four-color-deco

Abstract The purpose of this research is to investigate the color appearance and color connotation of unrelated colors. To investigate color appearance (i.e., brightness, colorfulness, and hue) for unrelated colors, 22 observers have answered their color appearance for 50 unrelated color stimuli using the magnitude estimation method. Perceptual data obtained by the experiment is compared with the color attributes data estimated by unrelated‐color appearance models, CAM97u and CAM02u. It is found

Abstract— Two newly derived characterization models for a liquid‐crystal (LC) display have been tested for five LC‐based displays. Data measured from a series of test colors indicated that all LC‐based displays showed similar characteristics, including an S‐shaped tone curve and poor channel chromaticity constancy. Because they include a hyperbolic function in their definition, the models do not have analytical inverses, and so iterative mathematical techniques are applied. It was shown that a n

The correlated color temperature (CCT) of the monitor white needs to be controlled for the preferred image reproduction according to the surround lighting changes. The preferred display white prediction model according to the surround lighting color is proposed both for the emissive transparent display and opaque displays. To develop the model, the preferred CCT of the monitor white of a simulated emissive transparent display and an opaque display were investigated under four different surround

Abstract The hue perception and ‘warm‐cool’ feelings were investigated, in response to various lighting settings, following the adaptation to either 3500K or 5000K to compare which one—between conventional iso‐Correlated Color Temperature (CCT) and a new one based on CIE u'v′ color space—is more compatible with the visual perception. Twenty participants evaluated hue and warm‐cool feelings for 48 test lighting settings, by observing an empty gray booth. The results showed that yellow‐blue and ‘w

In this study, the characterization method for a typical desktop LCD color projector is reviewed. Measurements were made with a spectroradiometer to establish the additivity of the primaries, inter-channel dependence, color gamut, tone scale, contrast, spatial non-uniformity, temporal stability and viewing angle variation. In the case of tone characterization, LCD projectors show S-shaped curve between input digital values and output luminance unlike the conventional CRT monitor represented by a

Abstract Correlated color temperature is widely used to describe colors of lights, but it has been questionable if it is well correlated to real perception. This study approached this issue with warm‐cool feelings, that is, the same correlated color temperature would evoke the same level of warm‐cool feelings. Since warm‐cool feeling is widely accepted to correlate closely with hue, a psychophysical experiment was performed to collect visual data of lights in terms of both hue and warm‐cool feel

Abstract The Images in an immersive head‐mounted display (HMD) for virtual reality provide the sole source for visual adaptation. Thus, significant, near‐instantaneous increases in luminance while viewing an HMD can result in visual discomfort. Therefore, the current study investigated the luminance change necessary to induce this discomfort. Based on the psychophysical experiment data collected from 10 subjects, a prediction model was derived using four complex images and one neutral image, wit

Display brightness data were collected under a wide range of surround conditions. A 24 in. (60.96 cm) LCD display was used to generate color stimuli, and a 107 in. (271.78 cm) two-dimensional illuminator was used to generate various surround conditions. The brightness values of the display under 89 monitor-surround-luminance combinations were collected from 10 or 24 observers. The surround ratio, S_R, i.e., the luminance ratio between the surround and the monitor, varied from 0 to 90.

The theoretical approach is introduced to design the optimal chromaticities for primaries of a display with a given size of triangular color gamut in xy-plane. Optimal primaries are defined as a set of chromaticities of red, green and blue primaries with fixed white point that most optimally satisfying four criteria, i.e. gamut size, gamut shape, coverage of object colors and hue of the primaries, in the visually uniform color space, CIECAM02. It is assumed that the optimal gamut should cover th

Experiments were conducted to investigate colour appearance under mesopic vision. Lightness, colourfulness and hue observations of 40 test colours were accumulated for eight phases with four different luminance levels covering 0.1 to 90 cd/m² and two different stimulus sizes corresponding to viewing angles of 2° and 10° using the magnitude estimation method. The psychophysical effects of luminance level and patch size on colour appearance were investigated and the role of the rods und

We present an experimental method to determine color appearance shifts under high-dynamic-range conditions. A couple of light booths with variable luminance provide high-dynamic-range luminance conditions, and a perceptual color shift between the two booths is determined using color appearance matching. For red, green, yellow, and blue groups of four surface color samples, color shifts were measured for nine subjects under a dual illumination at background luminance levels of $100\,\,{{\rm cd/m}