From 7d147f3576327e6390452834227e7ebec003dcf6 Mon Sep 17 00:00:00 2001
From: sam <sam@92316355-f0b4-4df1-b90c-862c8a59935f>
Date: Mon, 28 Jul 2008 23:01:21 +0000
Subject: [PATCH]   * Test implementation of Gaussian blurring. It's awfully
 slow and does not     use the separation property, but it's just for a test.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2603 92316355-f0b4-4df1-b90c-862c8a59935f
---
 pipi/Makefile.am   |  1 +
 pipi/filter/blur.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 pipi/pipi.h        |  2 ++
 3 files changed, 83 insertions(+)
 create mode 100644 pipi/filter/blur.c

diff --git a/pipi/Makefile.am b/pipi/Makefile.am
index 6625645..f49d330 100644
--- a/pipi/Makefile.am
+++ b/pipi/Makefile.am
@@ -27,6 +27,7 @@ libpipi_la_SOURCES = \
 	dither.c \
 	test.c \
 	$(codec_sources) \
+	filter/blur.c \
 	$(NULL)
 libpipi_la_CFLAGS = $(codec_cflags)
 libpipi_la_LDFLAGS = $(codec_libs) \
diff --git a/pipi/filter/blur.c b/pipi/filter/blur.c
new file mode 100644
index 0000000..ac6b28f
--- /dev/null
+++ b/pipi/filter/blur.c
@@ -0,0 +1,80 @@
+/*
+ *  libpipi       Proper image processing implementation library
+ *  Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
+ *                All Rights Reserved
+ *
+ *  $Id$
+ *
+ *  This library is free software. It comes without any warranty, to
+ *  the extent permitted by applicable law. You can redistribute it
+ *  and/or modify it under the terms of the Do What The Fuck You Want
+ *  To Public License, Version 2, as published by Sam Hocevar. See
+ *  http://sam.zoy.org/wtfpl/COPYING for more details.
+ */
+
+/*
+ * blur.c: blur functions
+ */
+
+#include "config.h"
+#include "common.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+#include "pipi.h"
+#include "pipi_internals.h"
+
+pipi_image_t *pipi_gaussian_blur(pipi_image_t const *src, float radius)
+{
+    pipi_image_t *dst;
+    double *kernel;
+    double K, L, t = 0.;
+    int x, y, i, j, w, h, kr, kw;
+
+    w = src->width;
+    h = src->height;
+
+    kr = (int)(3. * radius + 0.99999);
+    kw = 2 * kr + 1;
+    K = 1. / (2. * M_PI * radius * radius);
+    L = -1. / (2. * radius * radius);
+
+    kernel = malloc(kw * kw * sizeof(double));
+    for(j = -kr; j <= kr; j++)
+        for(i = -kr; i <= kr; i++)
+            t += kernel[(j + kr) * kw + (i + kr)]
+                     = exp(L * (i * i + j * j)) * K;
+
+    for(j = -kr; j <= kr; j++)
+        for(i = -kr; i <= kr; i++)
+            kernel[(j + kr) * kw + (i + kr)] /= t;
+
+    dst = pipi_new(w, h);
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            double R = 0., G = 0., B = 0.;
+
+            for(j = -kr; j <= kr; j++)
+                for(i = -kr; i <= kr; i++)
+                {
+                    double r, g, b, f = kernel[(j + kr) * kw + (i + kr)];
+
+                    pipi_getpixel(src, x + i, y + j, &r, &g, &b);
+                    R += f * r;
+                    G += f * g;
+                    B += f * b;
+                }
+
+            pipi_setpixel(dst, x, y, R, G, B);
+        }
+    }
+
+    return dst;
+}
+
diff --git a/pipi/pipi.h b/pipi/pipi.h
index a9a3128..b4f2303 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -40,6 +40,8 @@ extern int pipi_setpixel(pipi_image_t *img, int x, int y,
 
 extern pipi_image_t *pipi_resize(pipi_image_t const *, int, int);
 
+extern pipi_image_t *pipi_gaussian_blur(pipi_image_t const *, float);
+
 extern void pipi_dither_24to16(pipi_image_t *img);
 
 extern void pipi_test(pipi_image_t *);