Re: Acquiring Dental RVG on Linux
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/
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