Abstract
The CIECAM16 colour appearance model is currently a model with high prediction accuracy. It can solve the problem of predicting the influence of different observation conditions on the colour of gemstones. In this study, a computer vision system (CVS) was used to measure the colour of 59 bluish-green serpentinite samples, and the tristimulus values were input into the CIECAM16 forward model to calculate the colour appearance parameters of serpentinite under different surrounds, illuminances, and light sources. It was found that the darkening of the surround causes the lightness and brightness to increase. Pearson’s r of brightness and colourfulness with illuminance is 0.885 and 0.332, respectively, which predicts the Stevens and Hunt effects. When the light source changes from D65 to A, the calculated hue angle shifts to the complementary area of the A light source, which is contrary to the CVS measurement result. The D65 light source is more suitable for the colour presentation and classification of bluish-green serpentinite.
Highlights
Serpentinites are mainly composed of the serpentine mineral group, which includes hydrous phyllosilicates with an ideal chemical formula A3 Si2 O5 (OH)4, where A is Mg, Fe2+, and Ni [1]
The colour of bluishgreen serpentinite is mainly caused by the charge transition from Fe2+ to Fe3+, resulting in a broad absorption band centred at 630 nm, generating a weak, bluish-green hue [46]
The colour appearance observed by the human visual system is related to the tristimulus itself and to the field of view, which has four components: stimulus, proximal field, background, and surround
Summary
Serpentinites are mainly composed of the serpentine mineral group, which includes hydrous phyllosilicates with an ideal chemical formula A3 Si2 O5 (OH) , where A is Mg, Fe2+ , and Ni [1]. Many scholars have used infrared spectroscopy, Raman spectroscopy, X-ray powder diffractometry, and other analytical methods to study the mineralogical and petrological characteristics of serpentinites [4,5] Their deposits are widely distributed around the world. A shadowless dome light source colourIn temperature of 6500 k was adopted N9 in was lightnesses, ranging from N0.5with to aN9.5. The light source was placed shadowless dome light source with a colour temperature of 6500k was directly above the sample 9.5 cm away. Its interior was plated with a special diffuse reflective mater
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