Contrast-to-Noise Ratio on filaments
Filaments are grouped in sets of four differing by relative direction against the anode-cathode one. For every group the number of visible filaments is shown as well as the min, max and average CNR.
For each filament of a group, CNR is calculated using the following formula.
μD: mean pixel value of the detail ROI μB: mean pixel value of the background ROI σB: standard deviation of pixel values of the background ROI