Adding upstream version 2.10.36.upstream/2.10.36

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 935 insertions, 0 deletions

diff --git a/plug-ins/common/photocopy.c b/plug-ins/common/photocopy.c
new file mode 100644
index 0000000..5a2c7f2
--- /dev/null
+++ b/plug-ins/common/photocopy.c
@@ -0,0 +1,935 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* Photocopy filter for GIMP for BIPS
+ *  -Spencer Kimball
+ *
+ * This filter propagates dark values in an image based on
+ *  each pixel's relative darkness to a neighboring average
+ *  and sets the remaining pixels to white.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <libgimp/gimp.h>
+#include <libgimp/gimpui.h>
+
+#include "libgimp/stdplugins-intl.h"
+
+
+/* Some useful macros */
+
+#define PLUG_IN_PROC    "plug-in-photocopy"
+#define PLUG_IN_BINARY  "photocopy"
+#define PLUG_IN_ROLE    "gimp-photocopy"
+#define TILE_CACHE_SIZE 48
+#define GAMMA           1.0
+#define EPSILON         2
+
+
+typedef struct
+{
+  gdouble  mask_radius;
+  gdouble  sharpness;
+  gdouble  threshold;
+  gdouble  pct_black;
+  gdouble  pct_white;
+} PhotocopyVals;
+
+
+/*
+ * Function prototypes.
+ */
+
+static void      query  (void);
+static void      run    (const gchar       *name,
+                         gint               nparams,
+                         const GimpParam   *param,
+                         gint              *nreturn_vals,
+                         GimpParam        **return_vals);
+
+static void      photocopy        (GimpDrawable *drawable,
+                                   GimpPreview  *preview);
+static gboolean  photocopy_dialog (GimpDrawable *drawable);
+
+static gdouble   compute_ramp     (guchar       *dest1,
+                                   guchar       *dest2,
+                                   gint          length,
+                                   gdouble       pct_black,
+                                   gint          under_threshold);
+
+/*
+ * Gaussian blur helper functions
+ */
+static void      find_constants    (gdouble  n_p[],
+                                    gdouble  n_m[],
+                                    gdouble  d_p[],
+                                    gdouble  d_m[],
+                                    gdouble  bd_p[],
+                                    gdouble  bd_m[],
+                                    gdouble  std_dev);
+static void      transfer_pixels   (gdouble *src1,
+                                    gdouble *src2,
+                                    guchar  *dest,
+                                    gint     jump,
+                                    gint     width);
+
+/***** Local vars *****/
+
+const GimpPlugInInfo PLUG_IN_INFO =
+{
+  NULL,  /* init  */
+  NULL,  /* quit  */
+  query, /* query */
+  run,   /* run   */
+};
+
+static PhotocopyVals pvals =
+{
+  8.0,  /* mask_radius */
+  0.8,  /* sharpness */
+  0.75, /* threshold */
+  0.2,  /* pct_black */
+  0.2   /* pct_white */
+};
+
+
+/***** Functions *****/
+
+MAIN ()
+
+static void
+query (void)
+{
+  static const GimpParamDef args[] =
+  {
+    { GIMP_PDB_INT32,    "run-mode",    "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
+    { GIMP_PDB_IMAGE,    "image",       "Input image (unused)" },
+    { GIMP_PDB_DRAWABLE, "drawable",    "Input drawable" },
+    { GIMP_PDB_FLOAT,    "mask-radius", "Photocopy mask radius (radius of pixel neighborhood)" },
+    { GIMP_PDB_FLOAT,    "sharpness",   "Sharpness (detail level) (0.0 - 1.0)" },
+    { GIMP_PDB_FLOAT,    "pct-black",   "Percentage of darkened pixels to set to black (0.0 - 1.0)" },
+    { GIMP_PDB_FLOAT,    "pct-white",   "Percentage of non-darkened pixels left white (0.0 - 1.0)" }
+  };
+
+  gchar *help_string =
+    "Propagates dark values in an image based on "
+    "each pixel's relative darkness to a neighboring average. The idea behind "
+    "this filter is to give the look of a photocopied version of the image, "
+    "with toner transferred based on the relative darkness of a particular "
+    "region. This is achieved by darkening areas of the image which are "
+    "measured to be darker than a neighborhood average and setting other "
+    "pixels to white. In this way, sufficiently large shifts in intensity "
+    "are darkened to black. The rate at which they are darkened to black is "
+    "determined by the second pct_black parameter. The mask_radius parameter "
+    "controls the size of the pixel neighborhood over which the average "
+    "intensity is computed and then compared to each pixel in the neighborhood "
+    "to decide whether or not to darken it to black. Large values for "
+    "mask_radius result in very thick black areas bordering the regions "
+    "of white and much less detail for black areas everywhere including "
+    "inside regions of color. Small values result in less toner overall "
+    "and more detail everywhere. Small values for the pct_black make the "
+    "blend from the white regions to the black border lines smoother and "
+    "the toner regions themselves thinner and less noticeable; larger values "
+    "achieve the opposite effect.";
+
+  gimp_install_procedure (PLUG_IN_PROC,
+                          N_("Simulate color distortion produced by a copy machine"),
+                          help_string,
+                          "Spencer Kimball",
+                          "Bit Specialists, Inc.",
+                          "2001",
+                          N_("_Photocopy (legacy)..."),
+                          "RGB*, GRAY*",
+                          GIMP_PLUGIN,
+                          G_N_ELEMENTS (args), 0,
+                          args, NULL);
+
+  gimp_plugin_menu_register (PLUG_IN_PROC, "<Image>/Filters/Artistic");
+}
+
+static void
+run (const gchar      *name,
+     gint              nparams,
+     const GimpParam  *param,
+     gint             *nreturn_vals,
+     GimpParam       **return_vals)
+{
+  static GimpParam   values[2];
+  GimpRunMode        run_mode;
+  GimpDrawable      *drawable;
+  GimpPDBStatusType  status = GIMP_PDB_SUCCESS;
+
+  run_mode = param[0].data.d_int32;
+
+  /*  Get the specified drawable  */
+  drawable = gimp_drawable_get (param[2].data.d_drawable);
+
+  /*  set the tile cache size  */
+  gimp_tile_cache_ntiles (TILE_CACHE_SIZE);
+
+  *nreturn_vals = 1;
+  *return_vals  = values;
+
+  values[0].type          = GIMP_PDB_STATUS;
+  values[0].data.d_status = status;
+
+  INIT_I18N();
+
+  switch (run_mode)
+    {
+    case GIMP_RUN_INTERACTIVE:
+      /*  Possibly retrieve data  */
+      gimp_get_data (PLUG_IN_PROC, &pvals);
+
+      /*  First acquire information with a dialog  */
+      if (! photocopy_dialog (drawable))
+        return;
+      break;
+
+    case GIMP_RUN_NONINTERACTIVE:
+      pvals.mask_radius = param[3].data.d_float;
+      pvals.sharpness   = param[4].data.d_float;
+      pvals.pct_black   = param[5].data.d_float;
+      pvals.pct_white   = param[6].data.d_float;
+      break;
+
+    case GIMP_RUN_WITH_LAST_VALS:
+      /*  Possibly retrieve data  */
+      gimp_get_data (PLUG_IN_PROC, &pvals);
+      break;
+
+    default:
+      break;
+    }
+
+  if (status == GIMP_PDB_SUCCESS)
+    {
+      /*  Make sure that the drawable is RGB or GRAY color  */
+      if (gimp_drawable_is_rgb (drawable->drawable_id) ||
+          gimp_drawable_is_gray (drawable->drawable_id))
+        {
+          gimp_progress_init ("Photocopy");
+
+          photocopy (drawable, NULL);
+
+          if (run_mode != GIMP_RUN_NONINTERACTIVE)
+            gimp_displays_flush ();
+
+          /*  Store data  */
+          if (run_mode == GIMP_RUN_INTERACTIVE)
+            gimp_set_data (PLUG_IN_PROC, &pvals, sizeof (PhotocopyVals));
+        }
+      else
+        {
+          status        = GIMP_PDB_EXECUTION_ERROR;
+          *nreturn_vals = 2;
+          values[1].type          = GIMP_PDB_STRING;
+          values[1].data.d_string = _("Cannot operate on indexed color images.");
+        }
+    }
+
+  values[0].data.d_status = status;
+
+  gimp_drawable_detach (drawable);
+}
+
+/*
+ * Photocopy algorithm
+ * -----------------
+ * Mask radius = radius of pixel neighborhood for intensity comparison
+ * Threshold   = relative intensity difference which will result in darkening
+ * Ramp        = amount of relative intensity difference before total black
+ * Blur radius = mask radius / 3.0
+ *
+ * Algorithm:
+ * For each pixel, calculate pixel intensity value to be: avg (blur radius)
+ * relative diff = pixel intensity / avg (mask radius)
+ * If relative diff < Threshold
+ *   intensity mult = (Ramp - MIN (Ramp, (Threshold - relative diff))) / Ramp
+ *   pixel intensity *= intensity mult
+ * Else
+ *   pixel intensity = white
+ */
+static void
+photocopy (GimpDrawable *drawable,
+           GimpPreview  *preview)
+{
+  GimpPixelRgn  src_rgn, dest_rgn;
+  GimpPixelRgn *pr;
+  gint          x, y, width, height;
+  gint          bytes;
+  gboolean      has_alpha;
+  guchar       *dest1;
+  guchar       *dest2;
+  guchar       *src1, *sp_p1, *sp_m1;
+  guchar       *src2, *sp_p2, *sp_m2;
+  gdouble       n_p1[5], n_m1[5];
+  gdouble       n_p2[5], n_m2[5];
+  gdouble       d_p1[5], d_m1[5];
+  gdouble       d_p2[5], d_m2[5];
+  gdouble       bd_p1[5], bd_m1[5];
+  gdouble       bd_p2[5], bd_m2[5];
+  gdouble      *val_p1, *val_m1, *vp1, *vm1;
+  gdouble      *val_p2, *val_m2, *vp2, *vm2;
+  gint          i, j;
+  gint          row, col;
+  gint          terms;
+  gint          progress, max_progress;
+  gint          initial_p1[4];
+  gint          initial_p2[4];
+  gint          initial_m1[4];
+  gint          initial_m2[4];
+  gdouble       radius;
+  gdouble       val;
+  gdouble       std_dev1;
+  gdouble       std_dev2;
+  gdouble       ramp_down;
+  gdouble       ramp_up;
+
+  if (preview)
+    {
+      gimp_preview_get_position (preview, &x, &y);
+      gimp_preview_get_size (preview, &width, &height);
+    }
+  else
+    {
+      if (! gimp_drawable_mask_intersect (drawable->drawable_id,
+                                          &x, &y, &width, &height))
+        return;
+    }
+
+  bytes     = drawable->bpp;
+  has_alpha = gimp_drawable_has_alpha (drawable->drawable_id);
+
+  val_p1 = g_new (gdouble, MAX (width, height));
+  val_p2 = g_new (gdouble, MAX (width, height));
+  val_m1 = g_new (gdouble, MAX (width, height));
+  val_m2 = g_new (gdouble, MAX (width, height));
+
+  dest1 = g_new0 (guchar, width * height);
+  dest2 = g_new0 (guchar, width * height);
+
+  progress = 0;
+  max_progress = width * height * 3;
+
+  gimp_pixel_rgn_init (&src_rgn, drawable,
+                       x, y, width, height, FALSE, FALSE);
+
+  for (pr = gimp_pixel_rgns_register (1, &src_rgn);
+       pr != NULL;
+       pr = gimp_pixel_rgns_process (pr))
+    {
+      guchar *src_ptr  = src_rgn.data;
+      guchar *dest_ptr = dest1 + (src_rgn.y - y) * width + (src_rgn.x - x);
+
+      for (row = 0; row < src_rgn.h; row++)
+        {
+          for (col = 0; col < src_rgn.w; col++)
+            {
+              /* desaturate */
+              if (bytes > 2)
+                dest_ptr[col] = (guchar) gimp_rgb_to_l_int (src_ptr[col * bytes + 0],
+                                                            src_ptr[col * bytes + 1],
+                                                            src_ptr[col * bytes + 2]);
+              else
+                dest_ptr[col] = (guchar) src_ptr[col * bytes];
+
+              /* compute  transfer */
+              val = pow (dest_ptr[col], (1.0 / GAMMA));
+              dest_ptr[col] = (guchar) CLAMP (val, 0, 255);
+            }
+
+          src_ptr  += src_rgn.rowstride;
+          dest_ptr += width;
+        }
+
+      if (!preview)
+        {
+          progress += src_rgn.w * src_rgn.h;
+          gimp_progress_update ((gdouble) progress / (gdouble) max_progress);
+        }
+    }
+
+  /*  Calculate the standard deviations  */
+  radius   = MAX (1.0, 10 * (1.0 - pvals.sharpness));
+  radius   = fabs (radius) + 1.0;
+  std_dev1 = sqrt (-(radius * radius) / (2 * log (1.0 / 255.0)));
+
+  radius   = fabs (pvals.mask_radius) + 1.0;
+  std_dev2 = sqrt (-(radius * radius) / (2 * log (1.0 / 255.0)));
+
+  /*  derive the constants for calculating the gaussian from the std dev  */
+  find_constants (n_p1, n_m1, d_p1, d_m1, bd_p1, bd_m1, std_dev1);
+  find_constants (n_p2, n_m2, d_p2, d_m2, bd_p2, bd_m2, std_dev2);
+
+  /*  First the vertical pass  */
+  for (col = 0; col < width; col++)
+    {
+      memset (val_p1, 0, height * sizeof (gdouble));
+      memset (val_p2, 0, height * sizeof (gdouble));
+      memset (val_m1, 0, height * sizeof (gdouble));
+      memset (val_m2, 0, height * sizeof (gdouble));
+
+      src1  = dest1 + col;
+      sp_p1 = src1;
+      sp_m1 = src1 + (height - 1) * width;
+      vp1   = val_p1;
+      vp2   = val_p2;
+      vm1   = val_m1 + (height - 1);
+      vm2   = val_m2 + (height - 1);
+
+      /*  Set up the first vals  */
+      initial_p1[0] = sp_p1[0];
+      initial_m1[0] = sp_m1[0];
+
+      for (row = 0; row < height; row++)
+        {
+          gdouble *vpptr1, *vmptr1;
+          gdouble *vpptr2, *vmptr2;
+
+          terms = (row < 4) ? row : 4;
+
+          vpptr1 = vp1; vmptr1 = vm1;
+          vpptr2 = vp2; vmptr2 = vm2;
+
+          for (i = 0; i <= terms; i++)
+            {
+              *vpptr1 += n_p1[i] * sp_p1[-i * width] - d_p1[i] * vp1[-i];
+              *vmptr1 += n_m1[i] * sp_m1[i * width] - d_m1[i] * vm1[i];
+
+              *vpptr2 += n_p2[i] * sp_p1[-i * width] - d_p2[i] * vp2[-i];
+              *vmptr2 += n_m2[i] * sp_m1[i * width] - d_m2[i] * vm2[i];
+            }
+
+          for (j = i; j <= 4; j++)
+            {
+              *vpptr1 += (n_p1[j] - bd_p1[j]) * initial_p1[0];
+              *vmptr1 += (n_m1[j] - bd_m1[j]) * initial_m1[0];
+
+              *vpptr2 += (n_p2[j] - bd_p2[j]) * initial_p1[0];
+              *vmptr2 += (n_m2[j] - bd_m2[j]) * initial_m1[0];
+            }
+
+          sp_p1 += width;
+          sp_m1 -= width;
+          vp1   += 1;
+          vp2   += 1;
+          vm1   -= 1;
+          vm2   -= 1;
+        }
+
+      transfer_pixels (val_p1, val_m1, dest1 + col, width, height);
+      transfer_pixels (val_p2, val_m2, dest2 + col, width, height);
+
+      if (!preview)
+        {
+          progress += height;
+          if ((col % 5) == 0)
+            gimp_progress_update ((gdouble) progress / (gdouble) max_progress);
+        }
+    }
+
+  for (row = 0; row < height; row++)
+    {
+      memset (val_p1, 0, width * sizeof (gdouble));
+      memset (val_p2, 0, width * sizeof (gdouble));
+      memset (val_m1, 0, width * sizeof (gdouble));
+      memset (val_m2, 0, width * sizeof (gdouble));
+
+      src1 = dest1 + row * width;
+      src2 = dest2 + row * width;
+
+      sp_p1 = src1;
+      sp_p2 = src2;
+      sp_m1 = src1 + width - 1;
+      sp_m2 = src2 + width - 1;
+      vp1   = val_p1;
+      vp2   = val_p2;
+      vm1   = val_m1 + width - 1;
+      vm2   = val_m2 + width - 1;
+
+      /*  Set up the first vals  */
+      initial_p1[0] = sp_p1[0];
+      initial_p2[0] = sp_p2[0];
+      initial_m1[0] = sp_m1[0];
+      initial_m2[0] = sp_m2[0];
+
+      for (col = 0; col < width; col++)
+        {
+          gdouble *vpptr1, *vmptr1;
+          gdouble *vpptr2, *vmptr2;
+
+          terms = (col < 4) ? col : 4;
+
+          vpptr1 = vp1; vmptr1 = vm1;
+          vpptr2 = vp2; vmptr2 = vm2;
+
+          for (i = 0; i <= terms; i++)
+            {
+              *vpptr1 += n_p1[i] * sp_p1[-i] - d_p1[i] * vp1[-i];
+              *vmptr1 += n_m1[i] * sp_m1[i] - d_m1[i] * vm1[i];
+
+              *vpptr2 += n_p2[i] * sp_p2[-i] - d_p2[i] * vp2[-i];
+              *vmptr2 += n_m2[i] * sp_m2[i] - d_m2[i] * vm2[i];
+            }
+
+          for (j = i; j <= 4; j++)
+            {
+              *vpptr1 += (n_p1[j] - bd_p1[j]) * initial_p1[0];
+              *vmptr1 += (n_m1[j] - bd_m1[j]) * initial_m1[0];
+
+              *vpptr2 += (n_p2[j] - bd_p2[j]) * initial_p2[0];
+              *vmptr2 += (n_m2[j] - bd_m2[j]) * initial_m2[0];
+            }
+
+          sp_p1 ++;
+          sp_p2 ++;
+          sp_m1 --;
+          sp_m2 --;
+          vp1 ++;
+          vp2 ++;
+          vm1 --;
+          vm2 --;
+        }
+
+      transfer_pixels (val_p1, val_m1, dest1 + row * width, 1, width);
+      transfer_pixels (val_p2, val_m2, dest2 + row * width, 1, width);
+
+      if (!preview)
+        {
+          progress += width;
+          if ((row % 5) == 0)
+            gimp_progress_update ((gdouble) progress / (gdouble) max_progress);
+        }
+    }
+
+  /* Compute the ramp value which sets 'pct_black' % of the darkened pixels black */
+  ramp_down = compute_ramp (dest1, dest2, width * height, pvals.pct_black, 1);
+  ramp_up   = compute_ramp (dest1, dest2, width * height, 1.0 - pvals.pct_white, 0);
+
+  /* Initialize the pixel regions. */
+  gimp_pixel_rgn_init (&src_rgn, drawable, x, y, width, height, FALSE, FALSE);
+  gimp_pixel_rgn_init (&dest_rgn, drawable, x, y, width, height,
+                       (preview == NULL), TRUE);
+
+  pr = gimp_pixel_rgns_register (2, &src_rgn, &dest_rgn);
+
+  while (pr)
+    {
+      guchar  *src_ptr  = src_rgn.data;
+      guchar  *dest_ptr = dest_rgn.data;
+      guchar  *blur_ptr = dest1 + (src_rgn.y - y) * width + (src_rgn.x - x);
+      guchar  *avg_ptr  = dest2 + (src_rgn.y - y) * width + (src_rgn.x - x);
+      gdouble  diff, mult;
+      gdouble  lightness = 0.0;
+
+      for (row = 0; row < src_rgn.h; row++)
+        {
+          for (col = 0; col < src_rgn.w; col++)
+            {
+              if (avg_ptr[col] > EPSILON)
+                {
+                  diff = (gdouble) blur_ptr[col] / (gdouble) avg_ptr[col];
+
+                  if (diff < pvals.threshold)
+                    {
+                      if (ramp_down == 0.0)
+                        mult = 0.0;
+                      else
+                        mult = (ramp_down - MIN (ramp_down,
+                                                 (pvals.threshold - diff))) / ramp_down;
+                      lightness = CLAMP (blur_ptr[col] * mult, 0, 255);
+                    }
+                  else
+                    {
+                      if (ramp_up == 0.0)
+                        mult = 1.0;
+                      else
+                        mult = MIN (ramp_up,
+                                    (diff - pvals.threshold)) / ramp_up;
+
+                      lightness = 255 - (1.0 - mult) * (255 - blur_ptr[col]);
+                      lightness = CLAMP (lightness, 0, 255);
+                    }
+                }
+              else
+                {
+                  lightness = 0;
+                }
+
+              if (bytes < 3)
+                {
+                  dest_ptr[col * bytes] = (guchar) lightness;
+                  if (has_alpha)
+                    dest_ptr[col * bytes + 1] = src_ptr[col * src_rgn.bpp + 1];
+                }
+              else
+                {
+                  dest_ptr[col * bytes + 0] = lightness;
+                  dest_ptr[col * bytes + 1] = lightness;
+                  dest_ptr[col * bytes + 2] = lightness;
+
+                  if (has_alpha)
+                    dest_ptr[col * bytes + 3] = src_ptr[col * src_rgn.bpp + 3];
+                }
+            }
+
+          src_ptr  += src_rgn.rowstride;
+          dest_ptr += dest_rgn.rowstride;
+          blur_ptr += width;
+          avg_ptr  += width;
+        }
+
+      if (preview)
+        {
+          gimp_drawable_preview_draw_region (GIMP_DRAWABLE_PREVIEW (preview),
+                                             &dest_rgn);
+        }
+      else
+        {
+          progress += src_rgn.w * src_rgn.h;
+          gimp_progress_update ((gdouble) progress / (gdouble) max_progress);
+        }
+
+      pr = gimp_pixel_rgns_process (pr);
+    }
+
+  if (! preview)
+    {
+      gimp_progress_update (1.0);
+      /*  merge the shadow, update the drawable  */
+      gimp_drawable_flush (drawable);
+      gimp_drawable_merge_shadow (drawable->drawable_id, TRUE);
+      gimp_drawable_update (drawable->drawable_id, x, y, width, height);
+    }
+
+  /*  free up buffers  */
+  g_free (val_p1);
+  g_free (val_p2);
+  g_free (val_m1);
+  g_free (val_m2);
+  g_free (dest1);
+  g_free (dest2);
+}
+
+static gdouble
+compute_ramp (guchar  *dest1,
+              guchar  *dest2,
+              gint     length,
+              gdouble  pct,
+              gint     under_threshold)
+{
+  gint    hist[2000];
+  gdouble diff;
+  gint    count;
+  gint    i;
+  gint    sum;
+
+  memset (hist, 0, sizeof (int) * 2000);
+  count = 0;
+
+  for (i = 0; i < length; i++)
+    {
+      if (*dest2 != 0)
+        {
+          diff = (gdouble) *dest1 / (gdouble) *dest2;
+
+          if (under_threshold)
+            {
+              if (diff < pvals.threshold)
+                {
+                  hist[(int) (diff * 1000)] += 1;
+                  count += 1;
+                }
+            }
+          else
+            {
+              if (diff >= pvals.threshold && diff < 2.0)
+                {
+                  hist[(int) (diff * 1000)] += 1;
+                  count += 1;
+                }
+            }
+        }
+
+      dest1++;
+      dest2++;
+    }
+
+  if (pct == 0.0 || count == 0)
+    return (under_threshold ? 1.0 : 0.0);
+
+  sum = 0;
+  for (i = 0; i < 2000; i++)
+    {
+      sum += hist[i];
+      if (((gdouble) sum / (gdouble) count) > pct)
+        {
+          if (under_threshold)
+            return (pvals.threshold - (gdouble) i / 1000.0);
+          else
+            return ((gdouble) i / 1000.0 - pvals.threshold);
+        }
+    }
+
+  return (under_threshold ? 0.0 : 1.0);
+}
+
+
+/*
+ *  Gaussian blur helper functions
+ */
+
+static void
+transfer_pixels (gdouble *src1,
+                 gdouble *src2,
+                 guchar  *dest,
+                 gint     jump,
+                 gint     width)
+{
+  gint    i;
+  gdouble sum;
+
+  for(i = 0; i < width; i++)
+    {
+      sum = src1[i] + src2[i];
+      if (sum > 255) sum = 255;
+      else if(sum < 0) sum = 0;
+
+      *dest = (guchar) sum;
+
+      dest += jump;
+    }
+}
+
+static void
+find_constants (gdouble n_p[],
+                gdouble n_m[],
+                gdouble d_p[],
+                gdouble d_m[],
+                gdouble bd_p[],
+                gdouble bd_m[],
+                gdouble std_dev)
+{
+  gint    i;
+  gdouble constants [8];
+  gdouble div;
+
+  /*  The constants used in the implementation of a casual sequence
+   *  using a 4th order approximation of the gaussian operator
+   */
+
+  div = sqrt (2 * G_PI) * std_dev;
+  constants [0] = -1.783 / std_dev;
+  constants [1] = -1.723 / std_dev;
+  constants [2] = 0.6318 / std_dev;
+  constants [3] = 1.997  / std_dev;
+  constants [4] = 1.6803 / div;
+  constants [5] = 3.735 / div;
+  constants [6] = -0.6803 / div;
+  constants [7] = -0.2598 / div;
+
+  n_p [0] = constants[4] + constants[6];
+  n_p [1] = exp (constants[1]) *
+    (constants[7] * sin (constants[3]) -
+     (constants[6] + 2 * constants[4]) * cos (constants[3])) +
+       exp (constants[0]) *
+         (constants[5] * sin (constants[2]) -
+          (2 * constants[6] + constants[4]) * cos (constants[2]));
+  n_p [2] = 2 * exp (constants[0] + constants[1]) *
+    ((constants[4] + constants[6]) * cos (constants[3]) * cos (constants[2]) -
+     constants[5] * cos (constants[3]) * sin (constants[2]) -
+     constants[7] * cos (constants[2]) * sin (constants[3])) +
+       constants[6] * exp (2 * constants[0]) +
+         constants[4] * exp (2 * constants[1]);
+  n_p [3] = exp (constants[1] + 2 * constants[0]) *
+    (constants[7] * sin (constants[3]) - constants[6] * cos (constants[3])) +
+      exp (constants[0] + 2 * constants[1]) *
+        (constants[5] * sin (constants[2]) - constants[4] * cos (constants[2]));
+  n_p [4] = 0.0;
+
+  d_p [0] = 0.0;
+  d_p [1] = -2 * exp (constants[1]) * cos (constants[3]) -
+    2 * exp (constants[0]) * cos (constants[2]);
+  d_p [2] = 4 * cos (constants[3]) * cos (constants[2]) * exp (constants[0] + constants[1]) +
+    exp (2 * constants[1]) + exp (2 * constants[0]);
+  d_p [3] = -2 * cos (constants[2]) * exp (constants[0] + 2 * constants[1]) -
+    2 * cos (constants[3]) * exp (constants[1] + 2 * constants[0]);
+  d_p [4] = exp (2 * constants[0] + 2 * constants[1]);
+
+#ifndef ORIGINAL_READABLE_CODE
+  memcpy(d_m, d_p, 5 * sizeof(gdouble));
+#else
+  for (i = 0; i <= 4; i++)
+    d_m [i] = d_p [i];
+#endif
+
+  n_m[0] = 0.0;
+  for (i = 1; i <= 4; i++)
+    n_m [i] = n_p[i] - d_p[i] * n_p[0];
+
+  {
+    gdouble sum_n_p, sum_n_m, sum_d;
+    gdouble a, b;
+
+    sum_n_p = 0.0;
+    sum_n_m = 0.0;
+    sum_d   = 0.0;
+
+    for (i = 0; i <= 4; i++)
+      {
+        sum_n_p += n_p[i];
+        sum_n_m += n_m[i];
+        sum_d += d_p[i];
+      }
+
+#ifndef ORIGINAL_READABLE_CODE
+    sum_d++;
+    a = sum_n_p / sum_d;
+    b = sum_n_m / sum_d;
+#else
+    a = sum_n_p / (1 + sum_d);
+    b = sum_n_m / (1 + sum_d);
+#endif
+
+    for (i = 0; i <= 4; i++)
+      {
+        bd_p[i] = d_p[i] * a;
+        bd_m[i] = d_m[i] * b;
+      }
+  }
+}
+
+/*******************************************************/
+/*                    Dialog                           */
+/*******************************************************/
+
+static gboolean
+photocopy_dialog (GimpDrawable *drawable)
+{
+  GtkWidget *dialog;
+  GtkWidget *main_vbox;
+  GtkWidget *preview;
+  GtkWidget *table;
+  GtkObject *scale_data;
+  gboolean   run;
+
+  gimp_ui_init (PLUG_IN_BINARY, FALSE);
+
+  dialog = gimp_dialog_new (_("Photocopy"), PLUG_IN_ROLE,
+                            NULL, 0,
+                            gimp_standard_help_func, PLUG_IN_PROC,
+
+                            _("_Cancel"), GTK_RESPONSE_CANCEL,
+                            _("_OK"),     GTK_RESPONSE_OK,
+
+                            NULL);
+
+  gtk_dialog_set_alternative_button_order (GTK_DIALOG (dialog),
+                                           GTK_RESPONSE_OK,
+                                           GTK_RESPONSE_CANCEL,
+                                           -1);
+
+  gimp_window_set_transient (GTK_WINDOW (dialog));
+
+  main_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
+  gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 12);
+  gtk_box_pack_start (GTK_BOX (gtk_dialog_get_content_area (GTK_DIALOG (dialog))),
+                      main_vbox, TRUE, TRUE, 0);
+  gtk_widget_show (main_vbox);
+
+  preview = gimp_drawable_preview_new_from_drawable_id (drawable->drawable_id);
+  gtk_box_pack_start (GTK_BOX (main_vbox), preview, TRUE, TRUE, 0);
+  gtk_widget_show (preview);
+
+  g_signal_connect_swapped (preview, "invalidated",
+                            G_CALLBACK (photocopy),
+                            drawable);
+
+  table = gtk_table_new (4, 3, FALSE);
+  gtk_table_set_col_spacings (GTK_TABLE (table), 6);
+  gtk_table_set_row_spacings (GTK_TABLE (table), 6);
+  gtk_box_pack_start (GTK_BOX (main_vbox), table, FALSE, FALSE, 0);
+  gtk_widget_show (table);
+
+  /*  Label, scale, entry for pvals.amount  */
+  scale_data = gimp_scale_entry_new (GTK_TABLE (table), 0, 0,
+                                     _("_Mask radius:"), 100, 5,
+                                     pvals.mask_radius, 3.0, 50.0, 1, 5.0, 2,
+                                     TRUE, 0, 0,
+                                     NULL, NULL);
+
+  g_signal_connect (scale_data, "value-changed",
+                    G_CALLBACK (gimp_double_adjustment_update),
+                    &pvals.mask_radius);
+  g_signal_connect_swapped (scale_data, "value-changed",
+                            G_CALLBACK (gimp_preview_invalidate),
+                            preview);
+
+  /*  Label, scale, entry for pvals.amount  */
+  scale_data = gimp_scale_entry_new (GTK_TABLE (table), 0, 1,
+                                     _("_Sharpness:"), 50, 5,
+                                     pvals.sharpness, 0.0, 1.0, 0.01, 0.1, 3,
+                                     TRUE, 0, 0,
+                                     NULL, NULL);
+
+  g_signal_connect (scale_data, "value-changed",
+                    G_CALLBACK (gimp_double_adjustment_update),
+                    &pvals.sharpness);
+  g_signal_connect_swapped (scale_data, "value-changed",
+                            G_CALLBACK (gimp_preview_invalidate),
+                            preview);
+
+  /*  Label, scale, entry for pvals.amount  */
+  scale_data = gimp_scale_entry_new (GTK_TABLE (table), 0, 2,
+                                     _("Percent _black:"), 50, 5,
+                                     pvals.pct_black, 0.0, 1.0, 0.01, 0.1, 3,
+                                     TRUE, 0, 0,
+                                     NULL, NULL);
+
+  g_signal_connect (scale_data, "value-changed",
+                    G_CALLBACK (gimp_double_adjustment_update),
+                    &pvals.pct_black);
+  g_signal_connect_swapped (scale_data, "value-changed",
+                            G_CALLBACK (gimp_preview_invalidate),
+                            preview);
+
+  /*  Label, scale, entry for pvals.amount  */
+  scale_data = gimp_scale_entry_new (GTK_TABLE (table), 0, 3,
+                                     _("Percent _white:"), 50, 5,
+                                     pvals.pct_white, 0.0, 1.0, 0.01, 0.1, 3,
+                                     TRUE, 0, 0,
+                                     NULL, NULL);
+
+  g_signal_connect (scale_data, "value-changed",
+                    G_CALLBACK (gimp_double_adjustment_update),
+                    &pvals.pct_white);
+  g_signal_connect_swapped (scale_data, "value-changed",
+                            G_CALLBACK (gimp_preview_invalidate),
+                            preview);
+
+  gtk_widget_show (dialog);
+
+  run = (gimp_dialog_run (GIMP_DIALOG (dialog)) == GTK_RESPONSE_OK);
+
+  gtk_widget_destroy (dialog);
+
+  return run;
+}