Abstract: In order to realize accurate measurement of the area of tread defect, a new method of wheel
tread area extraction is proposed based on image distortion correction. Firstly, the improved colorful
image labeling watershed algorithm is adopted to segment the surface image of the side view. Then,
the geometric correction is perfomed according to different characteristics of the horizontal and
vertical distortion of tread surface image. In this process, the two segmentations and the perspective
transformation of tread area are completed. Finally, a correction image is obtained from the tread
angle. The experimental results reveal that this method can accurately segment and correct the side
view of the tread image, which lays a solid foundation for the accurate calculation of tread defect
area.

Key words: tread damage, colorful mage marked watershed algorithm, distortion rectifying;
perspective transformation, accurate measurement