Modelling Simultaneous Contrast Effect on Chroma Based on CAM16 Colour Appearance Model

2021 ◽  
pp. 71-76
Author(s):  
Yuechen Zhu ◽  
Ming Ronnier Luo
Keyword(s):  
Contrast Effect ◽  
Appearance Model ◽  
Simultaneous Contrast ◽  
Colour Appearance

Proposed modification to the CAM16 colour appearance model to predict the simultaneous colour contrast effect

2019 ◽  
Vol 2019 (1) ◽  
pp. 190-194
Author(s):  
Yuechen Zhu ◽  
Ming Ronnier Luo
Keyword(s):  
Contrast Effect ◽  
Colour Vision ◽  
Appearance Model ◽  
Matching Method ◽  
Colour Contrast ◽  
Normal Colour ◽  
Proposed Modification ◽  
Colour Appearance

Experiments were carried out to investigate the simultaneous colour contrast effect on a self-luminous display using colour matching method. The goals of this study were to accumulate a new visual dataset and to extend CAM16 to predict the simultaneous colour contrast effect. Five coloured targets together with a neutral grey were studied. A total of 132 test/background combinations were displayed on a calibrated display. Twenty normal colour vision observers performed colour matching in the experiment. In total, 2,640 matches were accumulated. The data were used to accurately model the lightness and hue contrast results. The model was also successfully tested using two independent datasets.

Modelling and modification of simultaneous lightness contrast effect using the Albers' pattern

2020 ◽  
Vol 2020 (1) ◽  
pp. 28-32
Author(s):  
Yuechen Zhu ◽  
Ming Ronnier Luo
Keyword(s):  
Contrast Effect ◽  
Colour Vision ◽  
High Accuracy ◽  
Appearance Model ◽  
Visual Data ◽  
Matching Method ◽  
Lightness Contrast ◽  
Normal Colour ◽  
Contrast Pattern ◽  
Colour Appearance

Experiments were carried out to investigate the simultaneous lightness contrast effect on a self-luminous display using simultaneous colour matching method. The Albers ' contrast pattern named ' double-crosses ' was used. The goals of this study were to model lightness contrast effect and modify it in the CAM16 colour appearance model. Five coloured targets were studied, and 41 test/background combinations were displayed on a calibrated display. Twenty normal colour vision observers performed colour matching in the experiment. In total, 820 matches were accumulated. The result shows present CAM16 has an unsatisfactory prediction for the effect, especially in the positive region which means the background is brighter than the target. Two models were established based on the visual data, i. e., with and without modification to the lightness difference in CAM16 space. Both of the models predict the effect with high accuracy and reliability.

Lightness And Luminance: Perceptual Qualities in Conditions Of Simultaneous Contrast

2021 ◽  
pp. 100-107
Author(s):  
Vladimir P. Budak ◽  
Anna Y. Vagina ◽  
Nikita S. Epikhov ◽  
Pavel A. Smirnov
Keyword(s):  
Visual Perception ◽  
Experimental Approach ◽  
Optimization Methods ◽  
Appearance Model ◽  
Simultaneous Contrast ◽  
Multi Objective Optimization ◽  
First Results ◽  
Appearance Models ◽  
Colour Appearance ◽  
Luminance Range

This article is devoted to the research of the influence of induction and crispening effects on the lightness of objects. The target of this research is to simplify and clarify the analysis of the light distributions derived from the results of lighting calculations and measurements, and also to form the recommendations for obtaining preferred lightness contrasts in the case of visual perception of objects on different backgrounds. To provide such possibilities, it is necessary to refine the model of the lightness calculation in modern colour appearance models, which, in turn, requires the results of new experiments to take into account the induction and crispening effects in the conditions of simultaneous contrast. The same experiment was established by Takasaki on visual perception of grey squares on grey backgrounds. The article substantiates the necessity to refine the results of the Takasaki experiment and conduct the new experimental approach in more strictly specified conditions and in the expanded luminance range to ensure conditions of the modern standards. Here we propose setting up an experiment that provides these refinements and considers the properties of the proximal field – the contour of objects. The search of the results uses multi-objective optimization methods. The first results of this experiment are presented, based on them, were formed proposals to determine the preferred luminance of objects to ensure the required levels of lightness contrast when working on specified backgrounds. The calculations of the lightness deviations obtained as the result of the experiment and in the CIECAM02 colour appearance model, are presented. The peculiarities of translations of lighting engineering literature in the field of modelling a light-colour environment are noted, which require clarification for a correct and reliable understanding of colour appearance models, for which is proposed to open a discussion on this subject.

Colour Image Enhancement using Perceptual Saturation and Vividness

2019 ◽  
Vol 2019 (1) ◽  
pp. 243-246
Author(s):  
Muhammad Safdar ◽  
Noémie Pozzera ◽  
Jon Yngve Hardeberg
Keyword(s):  
Image Quality ◽  
Image Enhancement ◽  
Test Performance ◽  
Appearance Model ◽  
Colour Space ◽  
Categorical Judgment ◽  
Saturation Scale ◽  
Colour Image ◽  
Colour Appearance ◽  
Future Test

A perceptual study was conducted to enhance colour image quality in terms of naturalness and preference using perceptual scales of saturation and vividness. Saturation scale has been extensively used for this purpose while vividness has been little used. We used perceptual scales of a recently developed colour appearance model based on Jzazbz uniform colour space. A two-fold aim of the study was (i) to test performance of recently developed perceptual scales of saturation and vividness compared with previously used hypothetical models and (ii) to compare performance and chose one of saturation and vividness scales for colour image enhancement in future. Test images were first transformed to Jzazbz colour space and their saturation and vividness were then decreased or increased to obtain 6 different variants of the image. Categorical judgment method was used to judge preference and naturalness of different variants of the test images and results are reported.

Testing Colour Appearance Model Based UCS Using HDR, WCG and COMBVD Datasets

2021 ◽  
Vol 2021 (29) ◽  
pp. 381-386
Author(s):  
Xu Qiang ◽  
Muhammad Safdar ◽  
Ming Ronnier Luo
Keyword(s):  
Correlation Coefficient ◽  
Power Factor ◽  
Marked Improvement ◽  
Appearance Model ◽  
Colour Difference ◽  
Similar Performance ◽  
Model Based ◽  
Test Models ◽  
Appearance Models ◽  
Colour Appearance

Two colour appearance models based UCSs, CAM16-UCS and ZCAM-QMh, were tested using HDR, WCG and COMBVD datasets. As a comparison, two widely used UCSs, CIELAB and ICTCP, were tested. Metrics of the STRESS and correlation coefficient between predicted colour differences and visual differences, together with local and global uniformity based on their chromatic discrimination ellipses, were applied to test models' performance. The two UCSs give similar performance. The luminance parametric factor kL, and power factor γ, were introduced to optimize colour-difference models. Factors kL and γ of 0.75 and 0.5, gave marked improvement to predict the HDR dataset. Factor kL of 0.3 gave significant improvement in the test of WCG dataset. In the test of COMBVD dataset, optimization provide very limited improvement.

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