Background: The medium and heavy plate surface defects can be divided
into two categories. One is the defects without the depth changes. Such defects are
called closed defects. The other is the defects with the depth changes. Such defects are
called open defects.
Objective: The purpose of this study is to provide an efficient patent for the open defects
detection of medium and heavy plate.
Method: A defects detection patent is proposed based on the theory of color photometric
stereo. A single multi-spectral line scan camera with a white line light source
is used to obtain the image of the medium and heavy plate surface. The determination
algorithm for open defects is presented and the image processing algorithm is also studied.
Results: The possibility of the presented patent is verified through industrial application experiments in a
steel plant. Experimental results show that the patent can realize online detection for the medium and
heavy plate surface open defects promptly and accurately.
Conclusion: The defects with the depth changes are called the open defects. The patent proposed in this
paper provides a new way of surface open defects inspection based on machine vision.