On Sat, Jan 02, 2021 at 12:26:52PM +0100, Sebastian Hilbert wrote: > "The maximum spatial resolution is described as ability to separate patterns > of black and > white lines and it is given in line pairs per millimeter ([lp/mm]). As > theoretical limit it is > described in the literature and com-prehensive that the maximum resolution is > achieved > if one black line is imaged on one pixel while one white line is imaged to > the neighbor > pixel."
I find [1] to be a good reference as well. If I imagine line pair to be equivalent of 2 pixels, the pixel width isn't matching with that. Essentially lp/mm is appearing coarser than pixel width and probably hence called 'true (measured) resolution' and may be they aren't expected to match. I tried both: 1. using pixel width compute pixels per meter 2. using lp/mm, assuming 1 lp is equivalent to 2 pixels compute pixels per meter. The latter is coming closer to the reality, but not sure it's accurate enough as yet. May be there was a gap between the finger and the sensor when trial x ray was taken as our attention was on usb interface rather than lengths (getting computed length smaller than the actual one of the portion of the finger). I need to go and gather more x rays carefully (may be using a coin to make the boundaries more accurate) before confirming which measure is accurate or whether something else is required or is just a fixed calibration factor is needed. [1] https://www.edmundoptics.com/knowledge-center/application-notes/imaging/resolution/
