In this example we stretch a histogram. The histogram is calculated for the
input image. The lower starting point as well es end point in the histogram is considered
as black and white. The input image is shifted by the black offset, and scaled by the white gain
so that the histogram is in the range 0 to 255.
To eliminate noise and single pixel from the calculation the minimum number of pixel threshold
H-Box MakeBadImage will make a picture having a bad histogram on purpose.