operations/common/unpremultiply.c

   1 /* This file is an image processing operation for GEGL
   2  *
   3  * GEGL is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 3 of the License, or (at your option) any later version.
   7  *
   8  * GEGL is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with GEGL; if not, see <https://www.gnu.org/licenses/>.
  15  *
  16  * Copyright 2006 Øyvind Kolås <pippin@gimp.org>
  17  */
  18
  19 #include "config.h"
  20 #include <glib/gi18n-lib.h>
  21
  22 #ifdef GEGL_PROPERTIES
  23
  24    /* no properties */
  25
  26 #else
  27
  28 #define GEGL_OP_POINT_FILTER
  29 #define GEGL_OP_NAME     unpremultiply
  30 #define GEGL_OP_C_SOURCE unpremultiply.c
  31
  32 #include "gegl-op.h"
  33
  34 static gboolean
  35 process (GeglOperation       *op,
  36          void                *in_buf,
  37          void                *out_buf,
  38          glong                samples,
  39          const GeglRectangle *roi,
  40          gint                 level)
  41 {
  42   glong   i;
  43   gfloat *in  = in_buf;
  44   gfloat *out = out_buf;
  45
  46   for (i=0; i<samples; i++)
  47     {
  48       int  j;
  49       for (j=0; j<3; j++)
  50         {
  51           if (in[3] != 0)
  52             out[j] = in[j] / in[3];
  53           else
  54             out[j] = 0.0;
  55         }
  56       out[3]=in[3];
  57       in += 4;
  58       out+= 4;
  59     }
  60   return TRUE;
  61 }
  62
  63
  64 static void
  65 gegl_op_class_init (GeglOpClass *klass)
  66 {
  67   GeglOperationClass            *operation_class;
  68   GeglOperationPointFilterClass *point_filter_class;
  69
  70   operation_class    = GEGL_OPERATION_CLASS (klass);
  71   point_filter_class = GEGL_OPERATION_POINT_FILTER_CLASS (klass);
  72
  73   point_filter_class->process = process;
  74
  75   gegl_operation_class_set_keys (operation_class,
  76     "name"        , "gegl:unpremultiply",
  77     "categories"  , "color",
  78     "title"       , _("Unpremultiply alpha"),
  79     "reference-hash", "1e2a03d51d8cc5868c1921fdee58b2c9",
  80     "description" , _("Unpremultiplies a buffer that contains pre-multiplied colors (but according to the babl format is not.)"),
  81     NULL);
  82 }
  83
  84 #endif