Use of the histogram in "Considers" (Continuation)

At the same time as the command "Gain" it is interesting to test the "Offset" command. Its effect on the histogram is to extend it towards the left... towards the low lights.
Here, it was strongly decreased and it is seen that the histogram came "to be stuck" on the left. What has as a consequence the loss of the half tone in the dark zones.
The following image shows a correct setting, and even if the image is not ideal for the demontration, one perceives the "clearing" of the dark zones (leaves at the foreground).

With excess, the half tone will disappear, first in low lights then in the medium lights... As image on left shows.
The histogram "is crushed" on the right