Operations → Histogram command which can also be executed by clicking the button on the tool bar

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calls up a window containing height distribution of surface points. Numerical data at the bottom of the window correspond to position of dashed vertical lines. If you don’t see the dashed vertical lines on the histogram they are probably placed at the left and the right border of the graph.

There is a line with parameters under the histogram:

• - surface height corresponding to the left mark on histogram,
• - surface height corresponding to the right mark on histogram,
• - the difference between these two marks,
• - relative area of a selected part of histogram as a percent of overall number of pixels in the image.

Menu command Histogram → Cutoff makes a height of each point on the outside of vertical lines equal to the height of the corresponding line position. It has an immediate effect on the surface image. The histogram is also replotted and can be significantly changed. The histogram appearance can be adjusted in a preferences dialog window. It is called up by the right mouse click on the histogram and is a standard one.