Tristimulus colorimeter

A tristimulus colorimeter, colloquially shortened to colorimeter, is used in digital imaging to profile and calibrate output devices. It takes a limited number of wideband spectral energy readings along the visible spectrum by using filtered photodetectors; e.g. silicon photodiodes.[1]

For other uses, see Colorimeter.
Color calibration of a monitor using ColorHug2, an open-source colorimeter, placed on the screen

A colorimeter with the known value of absolute error allows measuring (x,y)-chromaticity coordinates in red, green, blue and white colors. Measured values are used for calculation of LCD profile coefficients.[2]

Originally, three glass filters whose transmittance spectra mimicked the CIE color matching functions (shown below) were employed.[3] A filter bank may be used to decompose the individual color matching functions if more accuracy is desired.[4]

A camera or colorimeter is said to be colorimetric if it satisfies the Luther condition by Robert Luther (1868–1945) (also called the "Maxwell–Ives criterion"),[5] reducing observer metamerism color errors, if the product of the spectral responsivity of the photoreceptor and the spectral transmittance of the filters is a linear combination of the CMFs.[6]

A colorimeter or a digital camera with a color filter array can, under certain conditions, be used as an alternative to a spectrophotometer.[7][8]

The illuminant and observer conditions should be specified when citing a measurement (e.g. D65/10°).[9]

The quality of a colorimeter may be assessed using the means in CIE publication 179:2007.[10]

There are various calibration methods for tristimulus colorimeters.[11]

  • Color sensor of a colorimeter
    Color sensor of a colorimeter
  • The CIE 1931 XYZ color matching functions
    The CIE 1931 XYZ color matching functions

References
  1. Schanda, János; George Eppeldauer; Georg Sauter (2007). "Tristimulus Color Measurement of Self-Luminous Sources". In János Schanda (ed.). Colorimetry: Understanding the CIE System. Wiley Interscience. doi:10.1002/9780470175637.ch6. ISBN 978-0-470-04904-4.
  2. Zharinov I.O., Zharinov O.O. (2015). "Method of software-based compensation of technological variation in chromaticity coordinates of LCD panels". Scientific and Technical Journal of Information Technologies, Mechanics and Optics. 15 (3): 387–397. doi:10.17586/2226-1494-2015-15-3-387-397.
  3. Hunter, Richard Sewall (September 1942). "Photoelectric tristimulus colorimetry with three filters". JOSA. 32 (9): 509–538. doi:10.1364/JOSA.32.000509. hdl:2027/mdp.39015077308396.
  4. Eppeldauer, George (Nov–Dec 1998). "Spectral Response Based Calibration Method of Tristimulus Colorimeters" (PDF). Journal of Research of the National Institute of Standards and Technology. 103 (6): 615–619. doi:10.6028/jres.103.040. PMC 4890952. PMID 28009362.
  5. Luther, Robert T.D. [in German] (1927). "Aus dem Gebiet der Farbreizmetrik". Zeitschrift für technische Physik. 8: 540–558.
  6. Ohta, Noboru; Robertson, Alan R. (2005). "Measurement and Calculation of Colorimetric Values". Colorimetry. John Wiley & Sons, Ltd. p. 154. doi:10.1002/0470094745.ch5. ISBN 978-0-470-09472-3.
  7. Imai, Francisco H.; Berns, Roy S. (1999). "Spectral estimation using trichromatic digital cameras" (PDF). Proceedings of the International Symposium on Multispectral Imaging and Color Reproduction for Digital Archives. 42. Retrieved 2008-05-06.
  8. Solli, Martin (16 December 2004). "Filter characterization in digital cameras" (PDF). Retrieved 2008-05-06. {{cite journal}}: Cite journal requires |journal= (help)
  9. Sangwine, Stephen J.; Horne; Robin E. N. (1998). The Colour Image Processing Handbook. Springer. p. 41. ISBN 0-412-80620-7.
  10. CIE TC 2-16 "Characterization of the Performance of Tristimulus Colorimeters" (2007). Methods for characterising tristimulus colorimeters for measuring the colour of light. Publication 179:2007. Vienna: CIE Central Bureau. ISBN 978-3-901906-60-2.
  11. Gardner, James L. (May–June 2007). "Comparison of Calibration Methods for Tristimulus Colorimeters" (PDF). Journal of Research of the National Institute of Standards and Technology. 112 (3): 129–138. doi:10.6028/jres.112.010. PMC 4656001. PMID 27110460. Archived from the original (PDF) on 2008-05-28.
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