[IX,IY] = VL_GRAD(I) returns the gradient components IX,IY of the 2-D discrete function I. I must be a two-dimensional matrix. VL_GRAD() computes the gradient by using finite differences; specifically, it uses central differences for all but the boundary pixels, for which it uses forward/backward differences as appropriate.

Remark

  VL_GRAD() is similar to the MATLAB built-in GRADIENT() function, excepts that it supports different gradient approximations.

VL_GRAD() accepts the following options:

Type central

  Specify which type of finite differences to use for all but the boundary samples. TYPE can be one of 'central', 'forward', or 'backward'.

See also: GRADIENT(), VL_HELP().