This is how it prints on UV paper, https://cdn.hackaday.io/images/1013221548797737200.jpg . This is the calibration data recorded by imaging with the camera directly on a CMOS chip. You can count pixels.. this is what an expert needs to determine the quality. https://cdn.hackaday.io/files/21933938381472/calib_data.zip

More data is here https://cdn.hackaday.io/files/21933938381472/21measurements.... pixel 4.65 microns. You can use opencv to do the trick. I added a little script in this one.