lqr_carver_set_gradient_function — set the gradient function for an LqrCarver
object
#include <lqr.h>
void lqr_carver_set_gradient_function( | LqrCarver* carver, |
LqrGradFuncType gf_ind) ; |
Function lqr_carver_set_gradient_function
is used
to set the function of the gradient which will be used by
the LqrCarver
object pointed to by carver
in determining the relevance of a pixel (less relevant pixels being the ones which
tend to be crossed by the seams, and thus the ones affected by rescaling).
For each pixel, the gradient is computed for each direction as the difference
of the values of nighboring pixels, the value being computed as the average
over the colour channels multiplied by the alpha channel value (if present).
Possible values of the argument gs_ind
are:
LQR_GF_XABS
absolute value of the gradient in the direction of the rescaling
LQR_GF_SUMABS
sum of absolute values of the gradients in both directions
LQR_GF_NORM
gradient norm
LQR_GF_NULL
always returns 0
The default value for newly created LqrCarver
objects is LQR_GF_XABS
.
The value LQR_GF_NULL
can be used together with the function
lqr_carver_bias_add_area
(3) ant the like to override completely the
automatic feature detection.