- The Equalize transform specifies the desired histogram shape
- Actual and desired histograms are displayed on the same grid
- The actual histogram can be displayed either (1) linearly, i.e. without expansion ; or (2) expanded using a non-linear mapping ( appearing logarithmic )
- The desired histogram curve stays linear, regardless of the user-chosen histogram expansion
(1) adjusting the desired histogram, which is displayed using a linear curve, is difficult when the desired histogram has a very strong spike, causing lower values to be scaled down so much that they are hard to tweak. (2) Deviations of the desired histogram from the actual histogram are hard to visualize when the scales are respectively linear and non-linear.
Suggestion
Expand the desired histogram according to histogram expansion.