Michelin Recherche Et Technique S.a.

Compagnie Generale Des Etablissements Michelin

Compagnie Generale Des Establissements Michelin

Compagnie Generale Des Etablissments Michelin

Michelin Recherche Et Techniques S.a.

Guillaume Noyel

Jean-Paul Zanella

Claire Moreau

Yusi Shen

Alexandre Joly

Dominique Jeulin

Michel Bilodeau

Estelle Parra-Denis

A method for processing an image of a surface of a tire to be inspected is described. A three-dimensional digital image is captured of the surface, and each pixel of a plane of the image is assigned an item of information relating to an elevation of the pixel with respect to the surface. By utilizing of a morphological operator that uses a structuring element, a first transformation of the image of the surface is performed with aid of an opening and then of a closing, so as to tailor a grey level of pixels situated abnormally above or below the surface.

Analysis of the digital image of the external surface of a tyre and processing of false measurement points

A method for processing an image of a surface of a tire under inspection is described. A three-dimensional digital image of the surface is captured and, for each point of the captured image, a grey-level value corresponding to an elevation is assigned to the point. Utilizing a first morphological operator that uses a rectangular key element, a closure-type first transformation of the image of the surface is carried out. Utilizing a second morphological operator that uses a rectangular key element, an opening-type second transformation of the surface is carried out. For each point of the image, a grey-level value equal to a minimum value between a grey-level value at that point obtained in a preceding step and a grey-level value at that point is assigned, so as to eliminate false measurement points.

Analysis of the digital image of the internal surface of a tyre and processing of false measurement points

In a method for processing an image of a surface of a tire, a 3D digital image of the surface is captured, and each pixel of the captured image is assigned a grey level value proportional to an elevation of a corresponding point with respect to the surface. The pixels are placed in rows and columns. A search is made for zones of the surface that include pixels having a grey-level value lower than a given threshold. Boundaries of an encompassing box that includes one or more of the zones are determined. Inside the encompassing box, a grey-level value equal to a mean grey-level value of a set of reference pixels (K, s) positioned in a zone situated in immediate proximity to a pixel under consideration is assigned to each of the pixels whose grey-level value is lower than the given threshold.

Analysis of the digital image of the surface of a tyre and processing of non-measurement points

In a method of fast analysis of relief elements featuring on an inner surface of a tire, a three-dimensional image of the surface is captured, and each pixel of the image is assigned a greyscale value proportional to a topographical elevation of a point corresponding to the pixel, so as to obtain a starting image. The image is transformed into an orthogonal reference frame (OXY) in which an abscissa axis (OX) represents circumferential values and an ordinate axis (OY) represents radial values. Each point of the surface, i.e., each pixel, is assigned an altitude gradient value (f(p)) by comparing an elevation of the point with an elevation of a discrete and reduced number of points arranged on a straight line passing through a pixel being considered (p) and oriented in a circumferential direction.

Method of fast analysis of the relief elements featuring on the internal surface of a tyre

A tire appearance detection method includes:

Method of checking the appearance of the surface of a tyre

A method of determining relief markings on a tire's sidewall surface includes assigning, to each pixel of a three-dimensional image of the surface, a grey-level value proportional to an elevation point corresponding to the pixel, to obtain a starting image. Using linear structuring elements of successively increasing sizes and oriented circumferentially, a series of successive morphological openings is performed iteratively on the starting surface. An image value obtained after a morphological opening using a structuring element is subtracted from an image value obtained after a morphological opening using a structuring element of an immediately lower size, to obtain a succession of images flattened by differencing. A thresholding operation is performed on the images flattened by differencing, to obtain binary images. A set-theoretic union of values of each of the binary images is performed, to obtain a final binary image in which markings appear in relief.

Method for determining markings in relief on the outer surface of the sidewall of a tyre

A method of determining relief elements on a tire surface includes capturing a three-dimensional image of the surface and assigning to each pixel (i, j) of the image a grey-level value proportional to a topographic elevation of a point corresponding to the pixel, so as to obtain a starting image (&#x192;). The method also includes transforming the starting image (&#x192;) by a first top-hat operation, with aid of a first structuring element, so as to obtain an image (&#x192;) flattened by differencing, (&#x192;=&#x192;&#x2014;&#x3b3;(&#x192;)). The method further includes performing a thresholding operation on the image flattened by differencing, so as to obtain a segmented image, (T(&#x192;)=seg) in which relief elements appear white on a black background.

Method for determining elements in relief on the surface of a tyre

Method for detecting an anomaly on the surface of a tire comprising the following steps in the course of which: A&#x2014;the image of a given anomaly present on the surface of at least one tire is produced, B&#x2014;with the aid of a collection of filters, a multivariate image of the said surface is constructed in a space of the filters, in which each pixel is represented in the form of a pixel vector, the components of each pixel vector having a value corresponding to the value of this pixel in the image transformed with the aid of each of the filters of the said collection, C&#x2014;with the aid of a linear function, this multivariate image is transformed from the space of the filters into a spectral space of given dimension whose variables are the filters or combinations of filters of the said collection, so as to form a spectral image, D&#x2014;a classifier is constructed by determining, for this anomaly, those zones representative of the spectral space which contain, in a statistically representative manner, the points of the spectral image of the said anomaly transformed into the said spectral space.

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Clermont-Ferrand, France

Guillaume Noyel