Resolve high contrast saving of aligned images

[SimonEbert]

When saving aligned images (use_alignment_cache=True), the saved aligned image looks a bit different than the normally used images (looks like slightly higher contrast). This could be due to a misrepresentation in the script. It may be that it is not interfering with the rest of the script, but would be nice to exclude

[lisasophie]

As far as I understand, two things are going on here:

1. The cubic bivariate spline creates over- and undershoots. This explains why we have values below zero and a slightly altered histogram in this value range. Clipping these from the displayed values in QGIS gives us a very similar looking image. Of course only clipping on one side is not great, so we should think about some kind of clipping method for overshoots as well. Alternatively, we could think about using a differnt interpolation method.

2. In ImageProcessing.py we scale the values by 65535, but this is never resolved back to the original values, so the aligned image has much larger values. However, this does not change the relative brightness of the image and does not necessarily have to be changed imo.

Since you are the one more familiar with the alignment / interpolation process I did not try to fix this. I can take over and try some things out though, if you want :)

[SimonEbert]

It might have to do something with the interpolation. However, I mostly notice it in the tracking_results_.jpg visualization, so it might also be something about the exact plotting routine there. Since the images on which the tracking happens seem pretty similar to me, this is not an urgent issue and I can look into it at some point.