저휘도 조건에서 그레이스케일 기반 색차 평가 방법의 한계

Abstract

The grayscale method, which is widely used for collecting perceived color difference data, has been applied in the textile industry and in the development of color difference formulas. However, it has generally been conducted within a narrow color range and under high-luminance conditions. This study conducted a psychophysical experiment to evaluate the applicability of grayscale method under various luminance conditions and to determine whether reliable data can be obtained from non-expert participants. Three adaptation luminance conditions (99.34, 7.44, 1.56cd/m2) were implemented by attaching ND filters to a monitor. A total of ten naïve observers evaluated 192 pairs of color stimuli generated based on 12 color centers. The results showed that observer repeatability increased as luminance decreased. However, the coefficient of variation for reproducibility exceeded 20%, indicating low consistency in evaluation criteria. Furthermore, for color pairs containing only hue and chroma differences, the response values were significantly lower than the CIEDE2000 predictions. This suggests that participants had difficulty evaluating chroma and hue differences based on lightness. Additionally, the luminance of grayscale used as evaluation criterion also varied, which limited the assessment of perceptual changes due to luminance variation. These findings indicate that the grayscale method has limitation when applied to naïve observers and they highlight the need for a new experimental method.