Tristimulus colorimeter explained

A tristimulus colorimeter, colloquially shortened to colorimeter or colourimeter, 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]

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 by (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]

Notes and References

1. Book: Schanda, János. George Eppeldauer . Georg Sauter . Colorimetry: Understanding the CIE System. Wiley Interscience. 2007. 978-0-470-04904-4. Tristimulus Color Measurement of Self-Luminous Sources. 10.1002/9780470175637.ch6. János Schanda.
2. Method of software-based compensation of technological variation in chromaticity coordinates of LCD panels. Zharinov I.O., Zharinov O.O.. Scientific and Technical Journal of Information Technologies, Mechanics and Optics. 15. 3. 387–397. 2015. 10.17586/2226-1494-2015-15-3-387-397. free.
3. Photoelectric tristimulus colorimetry with three filters. JOSA. Richard Sewall. Hunter. September 1942. 32. 9. 509–538. 10.1364/JOSA.32.000509. 2027/mdp.39015077308396. free.
4. Spectral Response Based Calibration Method of Tristimulus Colorimeters. George. Eppeldauer. Journal of Research of the National Institute of Standards and Technology. 103. 6. Nov–Dec 1998. 615–619. 10.6028/jres.103.040. 28009362. 4890952.
5. Aus dem Gebiet der Farbreizmetrik. Luther. Robert T.D.. . 1927. Zeitschrift für technische Physik. 8. 540–558.
6. Book: Ohta, Noboru. Colorimetry. 10.1002/0470094745.ch5. 154. Robertson, Alan R. . 978-0-470-09472-3. Measurement and Calculation of Colorimetric Values. 2005. John Wiley & Sons, Ltd..
7. Imai, Francisco H. . Berns, Roy S. . 1999 . Spectral estimation using trichromatic digital cameras . Proceedings of the International Symposium on Multispectral Imaging and Color Reproduction for Digital Archives . 42 . 2008-05-06 .
8. Solli . Martin . 16 December 2004 . Filter characterization in digital cameras . 2008-05-06 .
9. Book: Sangwine, Stephen J.. The Colour Image Processing Handbook. Horne . Robin E. N. . 41. Springer. 1998. 0-412-80620-7.
10. Book: Methods for characterising tristimulus colorimeters for measuring the colour of light. CIE TC 2-16 "Characterization of the Performance of Tristimulus Colorimeters". 978-3-901906-60-2. Publication 179:2007. 2007. CIE Central Bureau. Vienna.
11. Gardner . James L. . Comparison of Calibration Methods for Tristimulus Colorimeters . Journal of Research of the National Institute of Standards and Technology . 112 . 3 . 129–138 . May–June 2007 . 10.6028/jres.112.010 . 27110460 . 4656001 . dead . https://web.archive.org/web/20080528051448/http://nvl.nist.gov/pub/nistpubs/jres/112/3/V112.N03.A01.pdf . 2008-05-28 .