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Comparison of digital photography and spectrometry for evaluating colour perception in humans and other trichromatic species


Digital photography and spectrometry are widely used for colour measurement, but both methods have a number of advantages and disadvantages. Comparative studies can help determine the most appropriate method for quantifying animal colour perception, but few have attempted to compare them based on colour model conversion. Here we compare colour measurements from digital photography and spectrometry in a controlled standard experimental environment using the three-dimensional colour space model CIE L*a*b* which is designed to approximate colour perception in humans and assess the repeatability and agreement of the two methods. For digital photography, we first extracted RGB values from each colour patch and transferred these to L*a*b* values using colour model conversion. For spectrometry, we measured the spectral reflectance (SR) value and subsequently transferred SR values to L*a*b* values. Using a consensus of correlation analysis, intraclass correlation coefficients, concordance correlation coefficients, and Bland-Altman analysis, we found that although spectrometry showed a slightly higher repeatability than photography, both methods were highly repeatable and showed a strong agreement. Furthermore, we used Bland-Altman analysis to derive the limits of agreement, which can be used as criteria for identifying when photography and spectrometry could be as a suitable alternative for measuring colour perception in humans and other trichromatic species. We suggest that our workflow offers a practical and logical approach that could improve how we currently study colour perception in trichromats.

Significance statement

Measuring colour efficiently and accurately is necessary for investigating the evolutionary biology of colour perception in animals. Digital photography and spectrometry are two methods widely used for colour measurement, but there are benefits and limitations to using either method. Comparative studies based on colour model conversion are therefore critical for helping researchers determine which method is most appropriate. Here we test the repeatability and agreement of the two measuring methods using standard colour patches, as a comparative case study of broader interest in measuring colour perception in humans and similar primates. Our results demonstrate that both methods are highly repeatable, and the two methods may be used interchangeably to measure colour perception in humans under experimental conditions.

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Availability of data and materials

The datasets generated and/or analysed during the current study are available in the Baidu Netdisk repository [] (Password: 8nsm).


SR :

Spectral reflectance


Intraclass correlation coefficient


Concordance correlation coefficient

LoA :

Limits of agreement

CR :

Coefficient of repeatability


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We would like to extend our sincere thanks to Yupei Yan for their help on the sample collection. We thank Dr. Guangzhan Fang for his support on data analysis. We thank Dr. Raul E. Diaz for his help in improving the English writing of this manuscript. We also sincerely thank two anonymous referees for reviewing the manuscript and their helpful comments.


This research was supported by the National Natural Science Foundation of China (Grant Nos. 31500316 to CY and 32070448 to NL). The funders had no role in the design of the study, the collection, analysis, and interpretation of data and in writing the manuscript.

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CY and NL conceived the ideas and designed methodology; CY and JW collected the data; CY and JW analysed the data; and CY, JW, NL, and HL led the writing of the manuscript. All authors contributed to drafts and gave final approval for publication.

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Correspondence to Nan Lyu.

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Yang, C., Wang, J., Lyu, N. et al. Comparison of digital photography and spectrometry for evaluating colour perception in humans and other trichromatic species. Behav Ecol Sociobiol 75, 151 (2021).

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  • Colour measurement
  • Digital photography
  • Spectrometry
  • CIE L * a * b *
  • ICC
  • Bland-Altman analysis