Geometry-invariant wrinkle detection in sealing rims of paperboard containers

Noticeable improvements were achieved in the method for quality evaluation of formed paperboard containers. The method now allows for in situ evaluation of unavoidable wrinkle structures along the sealing rim of formed containers. An image of the sealing rim was provided. In this image, the contour of the sample was detected. The contour line was then offset to the inside of the sample, so that the new line was on the sealing rim, regardless of the original contour geometry. Along this offset contour line, the wrinkle structure was evaluated by using a previously described cross-correlation-based method. The repeatability and accuracy of the method were validated by comparing the detection results with the results from thorough human examiners. Furthermore, an approach to find the optimum settings for the wrinkle detection program is described and an outlook on implications for industrial adaptation of this method is given.