The goal is to create a solution for automatically analyzing image of the AXIOM Beta PCBs we produce in various stages of assembly/production.
Very often the method is to compare areas of a known good reference image to an unknown PCB and report areas with differences (where match is below threshold).
Images are typically scanned with a flatbed scanner so the DPI is known.
A first step to preprocess an image for further matching analysis is properly aligning the PCB (rotation).
PCBs typically have so called fiducials (optical markers) with known location on the PCBs (these coordinates are supplied).
OpenCV.js: https://docs.opencv.org/3.3.1/d5/d10/tutorial_js_root.html