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Proceedings Paper

New approach to color calibration of high fidelity color digital camera by using unique wide gamut color generator based on LED diodes
Author(s): M. Kretkowski; Y. Shimodaira; R. Jabłoński
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Paper Abstract

Development of a high accuracy color reproduction system requires certain instrumentation and reference for color calibration. Our research led to development of a high fidelity color digital camera with implemented filters that realize the color matching functions. The output signal returns XYZ values which provide absolute description of color. In order to produce XYZ output a mathematical conversion must be applied to CCD output values introducing a conversion matrix. The conversion matrix coefficients are calculated by using a color reference with known XYZ values and corresponding output signals from the CCD sensor under each filter acquisition from a certain amount of color samples. The most important feature of the camera is its ability to acquire colors from the complete theoretically visible color gamut due to implemented filters. However market available color references such as various color checkers are enclosed within HDTV gamut, which is insufficient for calibration in the whole operating color range. This led to development of a unique color reference based on LED diodes called the LED Color Generator (LED CG). It is capable of displaying colors in a wide color gamut estimated by chromaticity coordinates of 12 primary colors. The total amount of colors possible to produce is 25512. The biggest advantage is a possibility of displaying colors with desired spectral distribution (with certain approximations) due to multiple primary colors it consists. The average color difference obtained for test colors was found to be ▵E≈0.78 for calibration with LED CG. The result is much better and repetitive in comparison with the Macbeth ColorCheckerTM which typically gives ▵E≈1.2 and in the best case ▵E≈0.83 with specially developed techniques.

Paper Details

Date Published: 17 November 2008
PDF: 9 pages
Proc. SPIE 7266, Optomechatronic Technologies 2008, 72661E (17 November 2008); doi: 10.1117/12.804737
Show Author Affiliations
M. Kretkowski, Shizuoka Univ. (Japan)
Warsaw Univ. of Technology (Poland)
Y. Shimodaira, Shizuoka Univ. (Japan)
R. Jabłoński, Warsaw Univ. of Technology (Poland)


Published in SPIE Proceedings Vol. 7266:
Optomechatronic Technologies 2008

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