I've added comments in my code. If still there is anything to do, please let
me know.
--
Sourav De
2nd Year Student
Department of Computer Science and Engineering
IIT KHARAGPUR
/****************************************************************************
* Blur:
*
* Blur applies a (2n+1)x(2n+1) blurring convolution kernel to the specified image.
*
* Where n is the blur radius specified by the user.
*
* This works only with RGB and grayscale images.
*
****************************************************************************/
#include "config.h"
#include <glib/gi18n-lib.h>
#ifdef GEGL_CHANT_PROPERTIES
gegl_chant_int (radius, _("Radius"), 0, 50, 3,
_("Blur Radius"))
#else
#define GEGL_CHANT_TYPE_AREA_FILTER
#define GEGL_CHANT_C_FILE "blur.c"
#include <gegl-chant.h>
#include <math.h>
#include <stdio.h>
static void blur(GeglBuffer *src,const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect,gint radius);
static inline void prepare(GeglOperation *operation)
{
GeglChantO *o = GEGL_CHANT_PROPERTIES (operation);
GeglOperationAreaFilter *area = GEGL_OPERATION_AREA_FILTER (operation);
area->left = area->right = area->top = area->bottom=o->radius;
gegl_operation_set_format (operation, "input", babl_format ("RaGaBaA float"));
gegl_operation_set_format (operation, "output", babl_format ("RaGaBaA float"));
}
static gboolean process (GeglOperation *operation, GeglBuffer *input, GeglBuffer *output, const GeglRectangle *result)
{
GeglChantO *o = GEGL_CHANT_PROPERTIES (operation);
GeglRectangle rect;
GeglOperationAreaFilter *op_area;
op_area = GEGL_OPERATION_AREA_FILTER (operation);
rect.x = result->x - op_area->left;
rect.width = result->width + op_area->left + op_area->right;
rect.y = result->y - op_area->top;
rect.height = result->height + op_area->top + op_area->bottom;
blur(input, &rect, output, result,o->radius);
return TRUE;
}
/*********************************
*
* blur()
*
* Actually mess with the image.
*
********************************/
static void blur (GeglBuffer *src,const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect,gint radius)
{
gint x,y;
gint i,j;
gint a,b;
gfloat *src_buf,*dst_buf;
gint offset;
src_buf = g_new0 (gfloat, src_rect->width * src_rect->height * 4);
dst_buf = g_new0 (gfloat, dst_rect->width * dst_rect->height * 4);
gegl_buffer_get (src, 1.0, src_rect, babl_format ("RaGaBaA float"), src_buf, GEGL_AUTO_ROWSTRIDE);
gint src_width=src_rect->width;
offset=0;
for(y=0; y<dst_rect->height; y++)
{
for (x=0; x<dst_rect->width; x++)
{
/* creates an array of length 4
first 3 elements are for Red, Green & Blue channel
last element is for no alpha channel */
gfloat gradient[4] = {0.0f, 0.0f, 0.0f, 0.0f};
gint c;
i=x+radius;
j=y+radius;
gfloat *src_pix = src_buf + (i + j * src_width) * 4;
/*The parameter radius determines the size of the area of source pixels,
that is averaged for each blurred destination pixel. */
for (c=0;c<4;c++)
{
for (a = -radius; a <= radius; ++a)
{
for (b = -radius; b <= radius; ++b)
gradient[c]+= src_pix[c+a*src_width*4+4*b];
}
gradient[c]/=pow((radius * 2 + 1),2);
}
/* transfers calculated average pixel values to the destination buffer */
for (c=0; c<4;c++)
dst_buf[offset*4+c] = gradient[c];
offset++;
}
}
gegl_buffer_set (dst, dst_rect, babl_format ("RaGaBaA float"), dst_buf,GEGL_AUTO_ROWSTRIDE);
g_free (src_buf);
g_free (dst_buf);
}
static void gegl_chant_class_init (GeglChantClass *klass)
{
GeglOperationClass *operation_class;
GeglOperationFilterClass *filter_class;
operation_class = GEGL_OPERATION_CLASS (klass);
filter_class = GEGL_OPERATION_FILTER_CLASS (klass);
filter_class->process = process;
operation_class->prepare = prepare;
operation_class->categories = "blur";
operation_class->name = "gegl:blur";
operation_class->description = _("Performs an averaging of pixels.");
}
#endif
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