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gradient

Arguments:

• { x | y | z | c }...{ x | y | z | c },_scheme,_boundary_conditions    or
• (no arg)

Description:

Compute the gradient components (first derivatives) of selected images, along specified axes.

(equivalent to shortcut command g).

scheme can be { -1:Backward | 0:Centered | 1:Forward | 2:Sobel | 3:Rotation-invariant (default) | 4:Deriche | 5:Vanvliet }.
boundary_conditions can be { 0:Dirichlet | 1:Neumann | 2:Periodic | 3:Mirror }.
(no arg) compute all significant components.

Default values:

scheme=0 and boundary_conditions=1.

This command has a tutorial page.

Example of use: