Basic methods for measuring the reflectance color of iron oxides

Pospíšil, Jiří; Hrdý, Jan

doi:10.1016/j.ijleo.2006.03.020

Cited by 7 publications

(4 citation statements)

References 18 publications

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“…The color change was determined by applying the model of the Commission Internationale de l'Eclaraige (CIE), using as a standard illuminant D 65 under an angle of 101 [21,22]. The color was described in terms of L n a n b n space color by CIE-LAB and CIELCH systems (CIE, 1976) [23], where the value of L n represents lightness (L n ¼0: black y L n ¼ 100: white), and a n and b n chromaticity (þ a n ¼red and -a n ¼green; þb n ¼yellow and À b n ¼blue) [24,25].…”

Section: Sample Characterizationmentioning

confidence: 99%

Thermal effects on the physical properties of limestones from the Yucatan Peninsula

González-Gómez

Quintana

May‐Pat

et al. 2015

International Journal of Rock Mechanics and Mining Sciences

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Section: Sample Characterizationmentioning

confidence: 99%

Thermal effects on the physical properties of limestones from the Yucatan Peninsula

González-Gómez

Quintana

May‐Pat

et al. 2015

International Journal of Rock Mechanics and Mining Sciences

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“…The average sRGB colour values of the pixels were obtained for representative regions of the material using software GIMP 2.10.12. The colour was described in terms of CIELAB space colour (CIE 1977), used by many authors (Pospíšil et al 2007;González-Gómez et al 2015) where L* represents lightness (i.e. the darkest black at L* = 0, and the brightest white at L* = 100), and a* and b* chromaticity.…”

Section: Materials and Methodologymentioning

confidence: 99%

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

et al. 2020

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In this investigation, two different varieties of 'Prada' limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400º C: i) the explosion of certain samples and ii) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400 and 500º C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally-treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO 2 from 400º C. This process jointly with the presence of micro-fissures in the 2 dark texture, would cause a dramatic increase in pore-pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400º C. That results also points towards a significant contribution of oxidation of pyrites on the thermochemical damage of the rock, among other factors such as the pre-existence of microfissuresand the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bear risk for mass fracturing and dramatic strength decay from 400º C. Moreover, SO 2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.

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“…represents the standardized CIE illuminant. Via comparing (7) and (8), an obvious difference between the tristimulus values is embodied in the device-independent and device-dependent color spaces and the color difference results from the illuminant and spectral response functions of digital sensor. Although the artificial standardized CIE D65 illuminator is adopted, the color temperature is about 6675 K (standard D65 is 6500 K) and the average color reproduction error is up to 3.25.…”

Section: Theoretical Basismentioning

confidence: 99%

“…Color measurement is essential for a very wide range of industrial applications including paint, paper, oil, skin, printing, food, plastics, and ceramic tile [1][2][3][4][5][6][7][8]. The superficial appearance and the color are regarded as the most important elements evaluated by consumers and are the critical factors for accepting the products by the consumers as well.…”

Section: Introductionmentioning

confidence: 99%

Color Calibration for Colorized Vision System with Digital Sensor and LED Array Illuminator

Zhu

Song

Luo

et al. 2016

Active and Passive Electronic Components

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Color measurement by the colorized vision system is a superior method to achieve the evaluation of color objectively and continuously. However, the accuracy of color measurement is influenced by the spectral responses of digital sensor and the spectral mismatch of illumination. In this paper, two-color vision system illuminated by digital sensor and LED array, respectively, is presented. The Polynomial-Based Regression method is applied to solve the problem of color calibration in the sRGB andCIE L⁎a⁎b⁎color spaces. By mapping the tristimulus values from RGB to sRGB color space, color difference between the estimated values and the reference values is less than3ΔE. Additionally, the mapping matrixΦRGB→sRGBhas proved a better performance in reducing the color difference, and it is introduced subsequently into the colorized vision system proposed for a better color measurement. Necessarily, the printed matter of clothes and the colored ceramic tile are chosen as the application experiment samples of our colorized vision system. As shown in the experimental data, the average color difference of images is less than6ΔE. It indicates that a better performance of color measurement is obtained via the colorized vision system proposed.

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Basic methods for measuring the reflectance color of iron oxides

Cited by 7 publications

References 18 publications

Thermal effects on the physical properties of limestones from the Yucatan Peninsula

Thermal effects on the physical properties of limestones from the Yucatan Peninsula

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

Color Calibration for Colorized Vision System with Digital Sensor and LED Array Illuminator

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