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28 mars 2023
- handle: 10670/1.a6wr1u
- hal: hal-04123962
- doi: 10.1088/2051-672X/acbe53
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info:eu-repo/semantics/altIdentifier/doi/10.1088/2051-672X/acbe53
info:eu-repo/semantics/OpenAccess
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Oil painting Paintings Painting, PrimitiveCiter ce document
Maxence Bigerelle et al., « Fractal and statistical characterization of brushstroke on paintings », HAL-SHS : histoire de l'art, ID : 10.1088/2051-672X/acbe53
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Résumé
Identification of an individual artist’s touch on paintings is studied using surface metrology. Paintings’ topographies were measured using focus variation and stitching, creating 13 × 13 mm maps with 1 μ m sampling intervals, and 169 megapixels, with a 10X objective lens. Topographic characterization parameters were analyzed for their ability to differentiate different painters’ renderings. Statistical treatments from data mining were used to discriminate, by optimization, multiscale topographic signatures characterized by a multitude of areal texture parameters. It appears that a fractal dimension can define 3 characteristic scale ranges. One from 3 to 70 μ m corresponds to brushstroke details. Another, from 70 to 700 μ m, corresponds to the topography of the material of the canvas fabric. Finally, scales greater than 700 μ m correspond to undulations of the canvas. For scales less than 50 μ m, the fractal structure of the topography left by brushstrokes follows a power law characterized by the slopes of the topography. The topography of the clouds painted on the canvas has an Sdq (topographic slopes) increasing with the clarity of the clouds at scales of 3–500 μ m. According to the Torrance-Sparrow theory, the higher the Sdq, the more diffuse the light on the surface. The painter therefore wanted to show, by his brushstroke, that the light clouds diffuse more light giving an impression of local brightness. This study is confirmed by the analysis of the painting of Max Savy, a French painter from Carcassonne (1918–2009), which was measured with a white light interferometer Zygo NewView 7300, a X100 objective lens giving a 517 μ m × 517 μ m stitched surface, with a sampling interval of 0.109 μ m. The box-counting method for estimating the fractal dimension of the topography of an oil painting appears optimal by the fact that it morphologically integrates scale variations of the local slopes of the surface morphology. This method thus characterizes the multiscale aspects, as well as the scale changes, of the topography.