NAME

       lqr_carver_bias_add_xy, lqr_carver_bias_add_area, lqr_carver_bias_add,
       lqr_carver_bias_add_rgb_area, lqr_carver_bias_add_rgb - update an LqrCarver bias

SYNOPSIS

       #include <lqr.h>

       LqrRetVal lqr_carver_bias_add_xy(LqrCarver* carver, gdouble bias, gint x, gint y);

       LqrRetVal lqr_carver_bias_add_area(LqrCarver* carver, gdouble* buffer, gint bias_factor,
                                          gint width, gint height, gint x_off, gint y_off);

       LqrRetVal lqr_carver_bias_add(LqrCarver* carver, gdouble* buffer, gint bias_factor);

       LqrRetVal lqr_carver_bias_add_rgb_area(LqrCarver* carver, gdouble* buffer,
                                              gint bias_factor, gint channels, gint width,
                                              gint height, gint x_off, gint y_off);

       LqrRetVal lqr_carver_bias_add_rgb(LqrCarver* carver, gdouble* buffer, gint bias_factor,
                                         gint channels);

FOREWORD

       All the functions described in this page are used to add a bias to LqrCarver objects. A
       positive biased pixel will be more likely to be avoided by seams, and thus be preserved
       during rescaling, while a negative bias has the opposite effect.

       All of these functions must be called before lqr_carver_resize(3). If called multiple
       times, the biases added at each call will sum up.

ADDING A BIAS PIXEL BY PIXEL

       The function lqr_carver_bias_add_xy adds a bias to the x, y pixel of the image loaded into
       the LqrCarver object pointed to by carver

       A typical value for bias_factor would be 1000 (in absolute value).

ADDING A BIAS FROM A BUFFER

       The function lqr_carver_bias_add_area adds a bias to an area of the image loaded into the
       LqrCarver object pointed to by carver.

       The parameter buffer must point to an array of doubles of size width * height, ordered
       first by rows, then by columns.

       The offset of the area relative to the image can be specified through x_off and y_off. The
       bias area can exceed the boundary of the image, and the offsets can be negative.

       The parameter bias_factor is an overall bias scale. A typical value when the buffer
       contents are of the order of 1 would be 1000 (in absolute value).

       The function lqr_carver_bias_add can be used when the area to add is of the same size of
       the image loaded in the LqrCarver object and the offsets are 0.

ADDING A BIAS FROM AN IMAGE

       The functions lqr_carver_bias_add_rgb_area and lqr_carver_bias_add_rgb are very similar to
       lqr_carver_bias_add_area and lqr_carver_bias_add, except that they use 8-bit multi-channel
       images as inputs.

       The number of channels in the image is passed via the parameter channels. The last channel
       is assumed to be the alpha (opacity) channel if channels is equal to 2 or greater than 3
       (if this is not the case, use the previous functions).

       The bias is computed from the average of the colour channels, multiplied by the value of
       the alpha channel if present. For example, in RGBA images a white, nontransparent pixel is
       equivalent to a value of 1.0 when using a buffer in lqr_carver_bias_add_area.

RETURN VALUES

       The return values follow the Liquid Rescale library signalling system.

SEE ALSO

       LqrRetVal(3), lqr_carver_init(3), lqr_carver_rigmask_add(3)

COPYRIGHT

       Copyright © 2007-2009 Carlo Baldassi