Exploring the applicability of the CAM18sl brightness prediction

Hermans, Stijn; Smet, Kevin; Hanselaer, Peter

doi:10.1364/oe.27.014423

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…As observers have to assign numeric estimates which represent ratio's, it is advised to test the math ability of observers prior to the experiment. ME has been used to investigate the effects of adaptation on perceived brightness (Stevens and Stevens 1963) and is frequently used to develop colour appearance models (CAM) such as CIECAM02 (Luo and Rhodes 1999;Moroney et al 2002), CAM15u (CIE 2004Withouck et al 2015b) and CAM18sl (Hermans et al 2018a(Hermans et al , 2019. However, ME can suffer from several disadvantages.…”

Section: Magnitude Estimationmentioning

confidence: 99%

A Comparison of Partition Scaling and Magnitude Estimation for Brightness Scaling

Perre

Smet

Dujardin

et al. 2020

LEUKOS

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Several psychophysical procedures exist to capture the relationship between the magnitude of an optical stimulus (e.g. luminance) and the corresponding perceived brightness. A commonly used psychophysical method is magnitude estimation (ME). However, some drawbacks of this method have been identified in literature: the method could be prone to some biases such as order effects, range effects and centring bias. On the other hand, partition scaling (PS) is one of the oldest, yet rarely used, psychophysical method to derive a similar luminance-brightness relationship. In the present study, the two methods are compared in terms of robustness and susceptibility to possible biases. Psychophysical experiments with simple achromatic discs were set up to obtain a brightness scale as a function of luminance using ME. Regarding PS, very similar experiments have been conducted in a previous study. The experiments were conducted for four luminance ranges: three subranges (low-, mid-and high-range of luminance) equally divided from 5 to 175 cd/m² and one overlapping full-range. Results indicate that observers had difficulties in accurately estimating the mid-and high-ranges for both methods, because the brightness between discs was too similar. Perceptual brightness scales could be obtained for the full-and low-range, although strong evidence was found for a range bias using ME. When pooling the full-and low-range data, both ME and PS results converge. Results show that PS is a valid alternative compared to ME for deriving brightness scales, with the advantage that it is more reliable and resilient to range bias.

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Section: Magnitude Estimationmentioning

confidence: 99%

A Comparison of Partition Scaling and Magnitude Estimation for Brightness Scaling

Perre

Smet

Dujardin

et al. 2020

LEUKOS

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“…Among all the perceptual attributes, brightness has been extensively investigated as such due to its important role in lighting and display applications, more particularly in defining glare levels or contrast threshold levels. [14][15][16][17] Multiple attempts have been reported in literature to model the mechanisms of brightness perception of a stimulus surrounded by a non-uniform background. Gilchrist et al 18 gave an extended discussion on the perception of lightness in complex images and proposed a lightness anchoring framework emphasizing that segments which belong to the same group (or Gestalt) of the target would influence the appearance of the target.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Brightness appearance of self‐luminous stimuli on a non‐uniform background

Phung

Kong

Leloup

et al. 2022

Color Research & Application

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Color appearance models (CAM) generate a set of visual correlates attributed to a stimulus such as hue, brightness, and saturation. However, most of their applicability is limited to stimuli perceived on a uniform background. Additionally, when focusing on brightness, multiple studies have been performed to model the mechanisms of brightness perception of a stimulus on a non‐uniform background. In this paper, experimental data are gathered and the insights of both approaches are combined. The influence of adding a neutral ring‐shaped luminous area in the background of a neutral circular stimulus has been investigated via a series of psychophysics experiments. The ring is presented at three luminance levels (90, 335, 1200 cd/m2) with three thicknesses (0.33, 0.67, and 1.00 cm) at four angular distances to the edge of the stimulus (1.2°, 6.4°, 11.3° and 16.1°). It is observed that when the ring is closer to the stimulus, the brightness inhibition becomes larger; obviously, the impact is also related to the ring's area and luminance. Inspired by the classical CAM, the cone excitations corresponding to the stimulus and the background are inserted in a compression‐adaptation formula to obtain a cone response proportional to the perceived brightness. The semi‐saturation constant occurring in this formula is modelled as a function of the cone excitation, the distance and the width of the ring. The results are overall promising, yet the model shows some shortcomings and more complex weighting functions might be needed. In the future, image‐based approaches should get more attention.

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Study of Color Rendering Evaluation Method of Light Sources for Printing Matter

Lian

Liu

et al. 2020

IEEE Access

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Based on the optimization of color samples, we have developed a method to evaluate light sources' color rendering of printing matter. By performing Affinity Propagation (AP) Clustering Algorithm on the color appearance and spectra of the color printing atlas samples printed by a press, two typical color sample sets are obtained. The optimized color sample (OCS) set consists of these two typical color sample sets and it is presented by CMYK dot area coverage. The color rendering indexes (CRIs) CIE-R a , CRI2012, CIE-R f of 90 light sources are calculated by taking the OCS set, color printing atlas and standard color sample (SCS) set of CRI as the test color sample (TCS) set. By comparing the Absolute Difference (AD), Mean Absolute Difference (MAD), Coefficient of Variation (CV) and Spearman Correlation Coefficient (SCC) of the CRIs, we find that the indexes calculated by OCS set are closer to these indexes calculated by color printing atlas than by SCS set. Therefore, the OCS set is more suitable for printing applications. After output from a press and measured spectra, the OCS set with CMYK dot area coverage can be used as the TCS set to evaluate the color rendering of light sources for all printing matter output from this press. For proving the reliability of the results, that is, the universality of the OCS set to the presses, the OCS set with fixed CMYK dot area coverage is output from an another press and CRIs are calculated. The results show that OCS set we developed is better than the SCS set. This method can be used for color rendering evaluation of light sources for printing matter.

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Exploring the applicability of the CAM18sl brightness prediction

Cited by 6 publications

References 14 publications

A Comparison of Partition Scaling and Magnitude Estimation for Brightness Scaling

A Comparison of Partition Scaling and Magnitude Estimation for Brightness Scaling

Brightness appearance of self‐luminous stimuli on a non‐uniform background

Study of Color Rendering Evaluation Method of Light Sources for Printing Matter

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