Reference image: weld strip with holes: https://i.sstatic.net/VaVQX3th.jpg

normal welding strip: https://i.sstatic.net/MBcyyIyp.jpg

I am having issues while detecting the defects (such as holes, non-uniformity) using opencv. I am new to opencv and tried contour detection, edge detection but not getting the desired results. I want to build an algorithm using opencv that detects those holes and marks them without marking any other unnecessary things which is not a defect.

I Looking for some help or guidance in this problem. Any kind of input or help will be appreciated. Thanks