.\"     Title: \fBlqr_carver_bias_add\fR
.\"    Author: Carlo Baldassi
.\" Generator: DocBook XSL Stylesheets v1.73.2 <http://docbook.sf.net/>
.\"      Date: 10 Maj 2009
.\"    Manual: LqR library API reference
.\"    Source: LqR library 0.4.1 API (3:1:3)
.\"
.TH "\FBLQR_CARVER_BIAS_ADD\FR" "3" "10 Maj 2009" "LqR library 0.4.1 API (3:1:3)" "LqR library API reference"
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.SH "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
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <lqr\&.h>
.fi
.ft
.HP 33
.BI "LqrRetVal lqr_carver_bias_add_xy(LqrCarver*\ " "carver" ", gdouble\ " "bias" ", gint\ " "x" ", gint\ " "y" ");"
.HP 35
.BI "LqrRetVal lqr_carver_bias_add_area(LqrCarver*\ " "carver" ", gdouble*\ " "buffer" ", gint\ " "bias_factor" ", gint\ " "width" ", gint\ " "height" ", gint\ " "x_off" ", gint\ " "y_off" ");"
.HP 30
.BI "LqrRetVal lqr_carver_bias_add(LqrCarver*\ " "carver" ", gdouble*\ " "buffer" ", gint\ " "bias_factor" ");"
.HP 39
.BI "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" ");"
.HP 34
.BI "LqrRetVal lqr_carver_bias_add_rgb(LqrCarver*\ " "carver" ", gdouble*\ " "buffer" ", gint\ " "bias_factor" ", gint\ " "channels" ");"
.SH "FOREWORD"
.PP
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\&.
.PP
All of these functions must be called before
\fBlqr_carver_resize\fR(3)\&. If called multiple times, the biases added at each call will sum up\&.
.SH "ADDING A BIAS PIXEL BY PIXEL"
.PP
The function
\fBlqr_carver_bias_add_xy\fR
adds a bias to the
\fIx\fR,
\fIy\fR
pixel of the image loaded into the
LqrCarver
object pointed to by
\fIcarver\fR
.PP
A typical value for
\fIbias_factor\fR
would be
1000
(in absolute value)\&.
.SH "ADDING A BIAS FROM A BUFFER"
.PP
The function
\fBlqr_carver_bias_add_area\fR
adds a bias to an area of the image loaded into the
LqrCarver
object pointed to by
\fIcarver\fR\&.
.PP
The parameter
\fIbuffer\fR
must point to an array of
\fBdoubles\fR
of size
\fIwidth\fR * \fIheight\fR, ordered first by rows, then by columns\&.
.PP
The offset of the area relative to the image can be specified through
\fIx_off\fR
and
\fIy_off\fR\&. The bias area can exceed the boundary of the image, and the offsets can be negative\&.
.PP
The parameter
\fIbias_factor\fR
is an overall bias scale\&. A typical value when the buffer contents are of the order of
1
would be
1000
(in absolute value)\&.
.PP
The function
\fBlqr_carver_bias_add\fR
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\&.
.SH "ADDING A BIAS FROM AN IMAGE"
.PP
The functions
\fBlqr_carver_bias_add_rgb_area\fR
and
\fBlqr_carver_bias_add_rgb\fR
are very similar to
\fBlqr_carver_bias_add_area\fR
and
\fBlqr_carver_bias_add\fR, except that they use 8\-bit multi\-channel images as inputs\&.
.PP
The number of channels in the image is passed via the parameter
\fIchannels\fR\&. The last channel is assumed to be the alpha (opacity) channel if
\fIchannels\fR
is equal to
2
or greater than
3
(if this is not the case, use the previous functions)\&.
.PP
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
\fBlqr_carver_bias_add_area\fR\&.
.SH "RETURN VALUES"
.PP
The return values follow the Liquid Rescale library signalling system\&.
.SH "SEE ALSO"
.PP

\fBLqrRetVal\fR(3), \fBlqr_carver_init\fR(3), \fBlqr_carver_rigmask_add\fR(3)
.SH "COPYRIGHT"
Copyright \(co 2007-2009 Carlo Baldassi
.br