Colour difference acceptability for calibrated digital images

Yu, D. K C; Oulton, David

doi:10.1080/13682199.2000.11784358

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…The size of the quoted delta E values may be interpreted by reference to the visual matching experiments of Yu and Oulton, 13 where object to image visual colour differences are quantified in terms of CMC (2 : 1) delta E. They found that a measured delta E(1 was typically reported as an acceptable colour match, and any difference delta E>3 was regarded as a poor match.…”

Section: Human Observer Resultsmentioning

confidence: 99%

Testing and optimizing the spectral response of digital cameras

Oulton¹,

Yu²

2005

The Imaging Science Journal

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A colorimetric analysis and design method for cameras is presented which enables a camera to be used as an imaging colorimeter, capable of capturing an accurate record of the Commission Internationale de l'É clairage (CIE) coordinates of the imaged objects. The spectral response characteristics of some of the component observers in the 1964 CIE Standard Observer average are first analysed and compared. CIE colour coordinates are calculated using both the Standard Observer average and individual observer CMFs for each of 32 test colours. The personal coordinates for each observer are then linked to differences in their visual response CMFs at the spectral level. A colorimetric testing and optimization method for cameras is then reported, which allows the colour capture properties of imaging systems to be analysed, controlled and modified. The method is based on imaging spectrally defined colour charts and is used to demonstrate that even minor differences in the chosen RGB filter/sensor characteristics substantially affect the numeric accuracy of the colour-defining information in images. Colour imaging error is quantified and minimized, first by establishing the camera RGB to CIE XYZ relationship, and then by adjusting the spectral response of the sensors. Under controlled lighting and exposure conditions, the design method enables output pixel-colour definitions that are a close analogue of the measured CIE XYZ tristimulus values for the imaged surface colours.

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Section: Human Observer Resultsmentioning

confidence: 99%

Testing and optimizing the spectral response of digital cameras

Oulton¹,

Yu²

2005

The Imaging Science Journal

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“…Instead, it aimed at being included as a useful color reference in high-end photography of objects [30]. It soon indeed became the de facto standard in high end photography [31], and even today it remains to be so in professional photography under the name X-Rite ColorChecker Classic [14]. When digital cameras became popular it was found that the MacBeth ColorChecker was less suitable for this task, as the colors of this chart cover only a relatively small color gamut [30].…”

Section: A) Original Colorcheckermentioning

confidence: 99%

Exploring the Limits of Color Accuracy in Technical Photography

Kirchner

Wijk

Beek

et al. 2021

Preprint

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The growing importance of publishing art collections online has led to increasingly strict tolerances on digital photography of art objects. There are two internationally recognized sets of guidelines for creating high-quality digital images, Metamorfoze and FADGI. These guidelines require using sets of standardized color patches in museal photography. The X-Rite ColorChecker SG chart with 140 color patches is often used. Recent studies showed that even in the standardized conditions of museum photography studios it is often very difficult to satisfy the strictest guidelines on color accuracy for camera profiling, with no indications for improvements.Here we report results of our investigation into the bottlenecks in achieving high color accuracy. We show that a large part of the color deviations originates from the 15 black color patches of the ColorChecker SG chart. These patches have a large impact on the average color deviation and the maximum color deviation that are the performance measures for color accuracy in the FADGI and Metamorfoze guidelines. We show that spectrophotometer measurements for the black patches produce color deviations dE(CIE 1976) ranging from 3.7 to 5.2 with respect to reference data, making it impossible to meet the strictest Metamorfoze guidelines. The black patches push the average color difference CIEDE2000 from 0.59 to 0.82 with respect to reference data already when using spectrophotometer data. Since the strictest FADGI guidelines prescribe an average CIEDE2000=2.0, this leaves little tolerance for errors due to lighting and camera profile. Our results indicate that the common practice of manually tweaking camera profiles until the software suggests sufficient color accuracy is obtained with respect to suppliers’ reference data often does not improve color representation but makes it worse, especially for representing dark nuances. This is unfortunate for example for the digital photography of 17th century Dutch paintings, where dark passages occupy large areas of the art works. We show that the key step in achieving color accurate digital photography is to use customer reference data rather than commonly used generic reference data. We explain the results by investigating not only the color properties of the ColorChecker SG chart, but also its glossiness.

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“…As mentioned, the cameras were of the type normally used by the retailer for security purposes, and earlier trials found that the focusing and angle of the in-store cameras were critical. Independent research Yu and Oulton (2000) has demonstrated that the quality of the image generated by the video cameras was vital to successful analysis. Because of the time-lapse function, the system only provided image quality with an approximate sampling rate of 5 frames per second.…”

Section: Data Collectionmentioning

confidence: 99%

New insights into retail space and format planning from customer-tracking data

Newman

Oulton

2002

Journal of Retailing and Consumer Services

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Recording and understanding the behaviour of customers is paramount and a key factor influencing the success of any retail business. This paper reports the initial stages of an EPSRC funded research project, which presents a new methodological approach to analysing in-store customer behaviour with a view to optimising space and store performance. Using existing in-store CCTV cameras from a major clothing discount retailer, consumers are tracked to detect patterns of behaviour. Analysis of these ''realtime'' data exhibited flaws in the arrangement of customer service facilities, and insight into the problems associated with merchandise return policies. Understanding these customer processes and movement patterns thus helped the retail collaborator maximise the performance of the store.

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Colour difference acceptability for calibrated digital images

Cited by 3 publications

References 2 publications

Testing and optimizing the spectral response of digital cameras

Testing and optimizing the spectral response of digital cameras

Exploring the Limits of Color Accuracy in Technical Photography

New insights into retail space and format planning from customer-tracking data

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