Mode

A gradient has two elements - contrast and direction. Of these, specify the element whose distribution is to be measured.

[Contrast]
The distribution of gradient contrasts is measured. A gradient contrast is represented by a value from 0 (weak) to 255 (strong). As shown in the example of the 'gradient contrast image' in the following figure, the value becomes larger at a place where there is a greater contrast between brightness and darkness.
[Original Image]
[Contrast Image]
Contrast
[Direction]
The distribution of gradient directions is measured. A gradient direction is represented by a value from 0 to 255. Numbers become larger as they go counterclockwise on the screen. Which direction is represented by each individual value is set in [Dir. at Middle Value].
[Original Image]
[Direction Image]
Direction