This exaggerated example shows
"posterization" or "banding" due to a lack of tones. The
histogram is combed with wide gaps between adjacent tones.
When performing image manipulations such as
tonal conversions in low bit environments (e.g. 8bits/channel mode)
only a limited number of tones may be available to describe a
certain area of the image, as shown in this exaggerated example.
This causes visible "banding" or "posterization".
