Wheelright Limited

Syed Wajahat Ali Shah Kazmi

Alexander Paul Codd

Peter Norman Rose

Ian Thomas Nabney

George Vogiatzis

A computer implemented method for generating a region of interest on a digital image of a sidewall of a tyre, the sidewall having one or more embossed and/or engraved markings, is provided. The method comprises generating a histogram of oriented gradients feature map of the digital image, inputting the histogram of oriented gradients feature map into a trained convolutional neural network, wherein said trained convolutional neural network is configured to output a first probability based on the input histogram of oriented gradients feature map that a region of pixels of the digital image contains the embossed and/or engraved markings, and if the first probability is at or above a first predetermined threshold, accepting said region of pixels as said region of interest.

Tyre sidewall imaging method

A computer implemented method is proposed for classifying one or more embossed and/or engraved markings on a sidewall of a tyre into one or more classes comprising digital image data of the sidewall of the tyre. The method comprises generating a first image channel from a first portion of the digital image data relating to a corresponding first portion of the sidewall of the tyre. Generating the first image channel comprises performing histogram equalisation on the first portion of the digital image data to generate the first image channel. The method further comprises generating a first feature map using the first image channel and applying a first classifier to the first feature map to classify said embossed and/or engraved markings into one or more first classes.

The condition of a tyre () on a wheel () is assessed while the wheel () is mounted on a vehicle () and while the vehicle () is moving. As the vehicle () moves, the tyre () rotates and moves longitudinally along a path of movement. An imaging device () captures images of a plurality of different portions () of the periphery of the tyre (), which has tread portions () separated by tread gaps (), whilst the tyre () revolves. While the images are being captured, longitudinally spaced flash units (F, F, F, F) are activated to illuminate portions () of the periphery of the tyre (). The flash units (F, F, F, F) are positioned to one side of the path of movement of the tyre () and direct light at an acute angle to the path of movement of the tyre () so that the light causes shadows to be cast in the tread gaps () between tread portions (). Each flash unit (F, F, F, F) causes a series of flashes of light to be produced when the flash unit (F, F, F, F) is activated, each flash of light in the series being separated from the next flash of light in the series by an interval. For any flash units (F, F, F, F) which are activated at the same time and illuminate overlapping portions of the periphery of tyre (), the respective series of flashes of light are out of phase so that the flashes of light from one flash unit (F, F, F, F) are emitted in the intervals between the flashes of light from the or each other flash unit (F, F, F, F). The images are analysed by data processing apparatus () to determine the extent of shadows in the tread gaps () so as to provide an indication of the depth of the tread gaps ().

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Oxfordshire, United Kingdom

Syed Wajahat Ali Shah Kazmi