The geometric mean has been suggested to be the fundamental mathematical relationship that governs peripheral sensory adaptation. This paper proposes the WGM model, an advanced chromatic adaptation model based on a weighted geometric mean approach that can anticipate incomplete adaptation as it moves along the Planckian or Daylight locus. Compared with two other chromatic adaptation models (CAT16 and vK20), the WGM model shows more accuracy in predicting previous visual data.
In ICC v4 colour management, data is exchanged between different colour encodings via a fixed Profile Connection Space (PCS), in which colorimetry is based on the D50 illuminant, and the CIE 1931 standard observer. According to the ICC specification, colorimetry that is based on a different illuminant, or observer should be transformed into the fixed PCS; however, while a chromatic adaptation method is specified for when illuminants are different, there is no method specified for differences in observer. The Waypoint method has been proposed as a means of transforming between different colorimetric data encodings. In this study a Waypoint-based method recommended by ICC was evaluated as a mechanism for transforming into the ICC PCS, as applied to a use case in digital textile printing in which source colorimetry is based on the D65 illuminant and the CIE 1964 observer. It was compared with an alternative approach in which a non-ICC PCS was used within a conventional ICC colour management framework. The results show that when both source and destination colorimetry are based on D65/10-degrees, both methods perform equally well. However, when the source and destination colorimetry do not match, the ICC approach of transforming via the standard PCS yields better results.
Two different experimental methods, method of adjustment and yellow/blue forced choice, were tested to investigate the time-course of chromatic adaptation. Inside the lighting booth, 2cmx2cm square color stimulus was displayed on the LCD display and the surface of the display was covered with gray paper except for the stimulus area. The lighting of the booth was controlled to have 3,000 K or 6,500 K with 800 lux at the bottom of the booth. During the adjustment method experiment, the observers adjusted the stimulus to preserve an achromatic appearance. In the forced-choice experiment, observers are asked to identify whether the stimuli are yellow or blue. In all experiments, evaluations were performed once every 5 seconds to track color appearance over time. CCT of the booth lighting was changed from 6,500 K to 3,000K or 3,000K to 6,500K every two minutes. The results showed that the observers had difficulties tracking the neutral colors using the adjustment method while the forced-choice experiment showed the more consistent results.
Accurately describing the effect of lighting on color appearance phenomena is critical for color science education. While it is ideal to conduct in-person tutorials to demonstrate the color appearance fundamentals, laboratory tutorials have been limited due to COVID-19. The limitation of in-person gatherings and the increase popularity of remote teaching help evoke alternative methods to demonstrate color appearance phenomena. Here, a remote tutorial method is described, and results are compared to in-person tutorials. While the remote tutorial had weaker result in representing observers' color experience compared to the in-person lab tutorial, remote demonstrations can be used to demonstrate and discuss the limitations of color imaging, and the difference between the human visual system and digital imaging systems.