The Minimum Intensity value at the bottom of the page returns the
lowest pixel value inside the regions of interest. The backlit edges of
the plastic cap appear in silhouette as dark pixels (which have low pixel
intensities) on a bright background (which has high pixel intensities).
Therefore, when the cap is present, the minimum intensity for the
regions is low. When the cap is not present, the minimum intensity for
the regions is high because the regions contain only bright background
pixels.
7. Enable the Minimum Intensity control. Set the Maximum value
to 50.00.