Amendment of CIECAM02 with a technical extension to compensate Helmholtz-Kohlrausch effect for chromatic characterization of display devices

Psychophysical experiments of colour appearance, in terms of lightness, colourfulness, and hue, were conducted outdoors and indoors to investigate whether there was any difference in colour appearance between outdoor and indoor environments. A panel of 10 observers participated in the outdoor experiment, while 13 observers took part in the indoor experiment. The reference white had an average luminance of 12784 cd/m 2 in the outdoor experiment and 129 cd/m 2 in the indoor experiment. Test colours included 42 colour patches selected from the Practical Coordinate Color System to achieve a reasonable uniform distribution of samples in CIECAM02. Experimental results show that for both outdoor and indoor environments, there was good agreement between visual data and predicted values by CIECAM02 for the three colour appearance scales, with the coefficient of variation values all lower than 25 and the R 2 values all higher than 0.73, indicating little difference in the three dimensions of colour appearance between indoor and outdoor viewing conditions. Experimental data also suggest that the observers were more sensitive to variation in lightness for grayish colours than for highly saturated colours, a phenomenon that seems to relate with the Helmholtz-Kohlrausch effect. This phenomenon was modeled for predicting perceived lightness (J 0 ) using the present experimental data. The new J 0 model was tested using three extra sets of visual data obtained both outdoors and indoors, showing good predictive performance of the new model, with an average coefficient of variation of 14, an average R 2 of 0.88, and an average STRESS index of 14.18.

Section: F I G U R E 4 Comparisons Between Visual Results and Predictmentioning

confidence: 99%

A comparison of colour appearance for surface colours between outdoor and indoor environments

Liang

2019

“…The H‐K effect is a well‐known color phenomenon, stating that for two stimuli with the same luminance, the more saturated one will be perceived as brighter. Different attempts have been made to include this phenomenon into CAMs . To evaluate the prediction of the H‐K effect by iCAM, a test has been performed using the same image configuration and experimental setup as described in the previous section.…”

Section: Evaluation Of Icam Performancementioning

confidence: 99%

“…Different attempts have been made to include this phenomenon into CAMs. 6,25 To evaluate the prediction of the H-K effect by iCAM, a test has been performed using the same image configuration and experimental setup as described in the previous section. A set of 30 colored stimuli (six different hues and five stimuli/hue) having a fixed luminance of 50 cd/m 2 is presented on a neutral background with (X, Y, Z) 10 , abs = [35.59, 33.65, 29.62], where Y 10 , abs represents the absolute 10 luminance in cd/m 2 .…”

Section: Prediction Of the Helmholtz-kohlrausch Effectmentioning

confidence: 99%

“…Since its introduction, CIECAM02 has been used in a wide range of industrial applications. Various improvements have been proposed to overcome some limitations of CIECAM02, such as considering the Helmholtz‐Kohlrausch (H‐K) effect, taking into account the stimulus size effect in the appearance of subject's colors, and solving some computational difficulties of CIECAM02 with a simpler model …”

Section: Introductionmentioning

confidence: 99%

“…Various improvements have been proposed to overcome some limitations of CIECAM02, such as considering the Helmholtz-Kohlrausch (H-K) effect, 6,7 taking into account the stimulus size effect in the appearance of subject's colors, 7,8 and solving some computational difficulties of CIECAM02 with a simpler model. 4 The availability of nonimaging CAMs to predict the color perception of self-luminous stimuli, such as luminaires, billboards, traffic signs, and displays, is much more limited.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessing the application of an image color appearance model to basic self‐luminous scenes

Phung

Leloup

Smet

et al. 2019

Image color appearance models (Image CAMs) have been developed to predict the perception of complex scenes and are mainly used for image rendering and video reproduction applications. Among these Image CAMs, iCAM is an Image CAM that takes an image as the input and provides the perceptual attributes for each pixel. On the other hand, nonimaging CAMs are widely used and validated, but they always assume a simple test scene of a uniform flat stimulus, a quasi‐neutral background, and a surround. This study presents an evaluation of the performance of iCAM when applied to these simple self‐luminous scenes in predicting the influence of background luminance, background size, saturation, and stimulus size on stimulus brightness. The results show that iCAM is capable of predicting the effect of background luminance and some background size scenarios. However, for unrelated self‐luminous stimuli (dark background), the model predictions do not match the reference data. An evaluation of the effect of the filter kernel size and its relation to the physiological mechanism of image processing inside the visual system has been investigated. Furthermore, the impact of saturation and stimulus size on brightness seems to be underestimated by the model, because the Helmholtz‐Kohlrausch and stimulus size effects are not included. Hence, these findings call for an enhanced Image CAM.

Extending CIECAM02 and CAM16 for the Helmholtz–Kohlrausch effect

Hellwig

Stolitzka

Fairchild

2022

Increasing the purity of a visual stimulus increases its brightness, even if the stimulus luminance is held constant. This perceptual phenomenon is known as the Helmholtz-Kohlrausch (H-K) Effect. This paper reviews published experimental data and models of the effect. Using past experimental data, we derive a modification of the CIECAM02 and CAM16 color appearance models to account for the H-K effect and compare the proposed model to other models. Finally, we discuss the need for further experimental data on the H-K effect to refine the proposed model.