Device and method for recognizing inscriptions on vehicle tires
A device for recognizing the inscription on the wall of a tire, including a driving surface plane, at least one directional light source to illuminate the tire; at least one camera to record multiple images of a wall of the tire rolling on the driving surface plane; and an evaluation device to synthesize an image of the wall of the tire from the multiple recorded images and to evaluate the synthesized image with the aid of a text recognition method.
1. A device for recognizing an inscription on a tire of a vehicle, comprising;
a driving surface plane;
at least one directional light source to illuminate the tire;
at least one camera to record an image sequence comprising multiple images of a wall of a tire rolling on the driving surface plane; and
a synthesizer configured to determine movement of local image areas between two arbitrary images of the image sequence using an algorithm and the knowledge that individual points on the wall of the tire move along a cycloid during the rolling thereby obtaining parameters of the corresponding cycloid movement for each image area; and to synthesize, based on said parameters, a central image of the wall of the tire, in which all edges of the inscription are represented with high contrast, from the images of the image sequence, and to evaluate the synthesized central image with the aid of a text recognition method.
2. The device of claim 1 , wherein multiple light sources are situated in a line along the rolling direction of the tire.
3. The device of claim 1 , wherein multiple light sources are in different vertical distances from the driving surface plane.
4. The device of claim 1 , wherein multiple light sources are in various positions across the rolling direction of the tire.
5. The device of claim 1 , wherein at least one of the at least one directional light sources has separately controllable lighting elements.
6. The device of claim 1 , wherein multiple light sources are configured to illuminate the tire with light of different wavelengths.
7. The device of claim 1 , wherein at least one of the at least one directional light sources is operable in a flash mode.
8. The device of claim 1 , further comprising:
a mirror arrangement to deflect natural sunlight and/or light of at least one headlight of the vehicle onto the wall of at least one tire.
9. A method for recognizing an inscription on a wall of a tire, the method comprising:
illuminating the tire with at least one directional light source;
recording an image sequence comprising multiple images of the wall of the tire rolling as it passes by at least one camera;
determining movement of local image areas between two arbitrary images of the image sequence using an algorithm and the knowledge that individual points on the wall of the tire move along a cycloid during the rolling thereby obtaining parameters of the corresponding cycloid movement for each image area;
synthesizing, based on said parameters, a central image of the wall of the tire, in which all edges of the inscription are represented with high contrast, from the images of the image sequence; and
evaluating the synthesized central image with the aid of a text recognition process.