Image histograms look a bit strange. As data is coded in 255 levels and the histogram has only 200 columns the data seems to be reagruped in a truncated manner giving a pretty suprising look of spykes.
This is probably due to aliasing in which the sampling of the histogram is incorrect for the image bit depth.
If you are using the histogram data tool in which you can set the number of bins, you should set it to twice the number of levels, i.e., for an 8-bit image, set the # of bins to 512.
Well, I wasn’t using the displayhistogram module it was with the “Show histogram” that you can get by right-clicking on the image, but I’ll check it out