lqr_carver_get_energy(3) [debian man page]

LQR_CARVER_GET_ENERGY(3)				     LqR library API reference					  LQR_CARVER_GET_ENERGY(3)

NAME

       lqr_carver_get_energy, lqr_carver_get_true_energy, lqr_carver_get_energy_image - get the energy map for a LqrCarver object

SYNOPSIS

       #include <lqr.h>

       LqrRetVal lqr_carver_get_energy(LqrCarver* carver, gfloat * buffer, gint orientation);

SYNOPSIS

       #include <lqr.h>

       LqrRetVal lqr_carver_get_true_energy(LqrCarver* carver, gfloat * buffer, gint orientation);

SYNOPSIS

       #include <lqr.h>

       LqrRetVal lqr_carver_get_energy(LqrCarver* carver, void * buffer, gint orientation, LqrColDepth col_depth, LqrImageType image_type);

DESCRIPTION

       The function lqr_carver_get_energy writes the energy map of the LqrCarver object pointed to by carver to the given buffer, in a format
       suitable for plotting: all values are in the range between 0 and 1, and the true values are mapped nonlinearly and stretched on this whole
       range, so that the differences between the middle values are enhanced with respect to very high or very low values.

       The orientation parameter must be either 0 to get the energy map used for horizontal scalings, or 1 to get the map for vertical scalings.

       The buffer must be allocated by the user before calling this function, and its size must be at least width * height, where width and height
       are the current width and height of the carver. The energy values are ordered by row first, then by column.

       The outcome will include the effect of the bias added to the carver, if any.

       This function can be called over non-initialised LqrCarver objects, e.g. to provide previews on the effect of different energy functions,
       but it can also be invoked at any later time. Note, however, that in this latter case the carver could be flattened if necessary, therefore
       the function invocation is potentially destructive of the internal visibiliy map.

       The function lqr_carvet_get_true_energy is identical to the previous one, but the resulting buffer will contain the true energy, not scaled
       nor shifted.

       The function lqr_carver_get_energy_image is very similar to the function lqr_carveR_get_energy, but it can be used to fill directly an
       image buffer of the format specified through the additional parameters col_depth and image_type (see LqrColDepth(3) and LqrImageType(3)).
       The buffer must be passed as void*, but it must point to a memory area with sufficient allocated space for the chosen image type and colour
       depth. The image type cannot be LQR_CUSTOM_IMAGE.

       For any choice of the parameters describing the image, the resulting buffer will hold a greyscale image, ranging from black (lowest energy)
       to white (highest energy). The opacity (alpha) will be set to 1, if present. All the information will be stored in the black channel in
       LQR_CMYK_IMAGE and LQR_CMYKA_IMAGE image types.

RETURN VALUES

       The return values follow the Liquid Rescale library signalling system. The function lqr_carver_get_energy_image will return an error if
       image_type is LQR_CUSTOM_IMAGE.

SEE ALSO

       lqr_carver_set_energy_function_builtin(3), lqr_carver_set_energy_function(3), lqr_carver_bias_add(3)

COPYRIGHT

       Copyright (C) 2007-2009 Carlo Baldassi

LqR library 0.4.1 API (3:1:3)					    10 Maj 2009 					  LQR_CARVER_GET_ENERGY(3)

LQR_CARVER_BIAS_ADD(3)					     LqR library API reference					    LQR_CARVER_BIAS_ADD(3)

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 (C) 2007-2009 Carlo Baldassi

LqR library 0.4.1 API (3:1:3)					    10 Maj 2009 					    LQR_CARVER_BIAS_ADD(3)