diff --git a/pipi/Makefile.am b/pipi/Makefile.am
index daae164..7c4cbb8 100644
--- a/pipi/Makefile.am
+++ b/pipi/Makefile.am
@@ -29,6 +29,7 @@ libpipi_la_SOURCES = \
 	test.c \
 	$(codec_sources) \
 	filter/blur.c \
+	filter/convolution.c \
 	dither/floydsteinberg.c \
 	dither/ostromoukhov.c \
 	dither/dbs.c \
diff --git a/pipi/filter/convolution.c b/pipi/filter/convolution.c
new file mode 100644
index 0000000..e00b721
--- /dev/null
+++ b/pipi/filter/convolution.c
@@ -0,0 +1,112 @@
+/*
+ *  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.
+ */
+
+/*
+ * convolution.c: generic convolution 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_convolution(pipi_image_t *src, int m, int n, double mat[])
+{
+    pipi_image_t *dst;
+    pipi_pixels_t *srcp, *dstp;
+    float *srcdata, *dstdata;
+    int x, y, i, j, w, h, gray;
+
+    w = src->w;
+    h = src->h;
+
+    gray = (src->last_modified == PIPI_PIXELS_Y_F);
+
+    srcp = gray ? pipi_getpixels(src, PIPI_PIXELS_Y_F)
+                : pipi_getpixels(src, PIPI_PIXELS_RGBA_F);
+    srcdata = (float *)srcp->pixels;
+
+    dst = pipi_new(w, h);
+    dstp = gray ? pipi_getpixels(dst, PIPI_PIXELS_Y_F)
+                : pipi_getpixels(dst, PIPI_PIXELS_RGBA_F);
+    dstdata = (float *)dstp->pixels;
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            if(gray)
+            {
+                double Y = 0.;
+                int x2, y2;
+
+                for(j = 0; j < n; j++)
+                {
+                    y2 = y + j - n / 2;
+                    if(y2 < 0) y2 = 0;
+                    else if(y2 >= h) y2 = h - 1;
+
+                    for(i = 0; i < m; i++)
+                    {
+                        x2 = x + i;
+                        if(x2 < 0) x2 = 0;
+                        else if(x2 >= w) x2 = w - 1;
+
+                        Y += mat[j * m + i] * srcdata[y * w + x2];
+                    }
+                }
+
+                dstdata[y * w + x] = Y;
+            }
+            else
+            {
+                double R = 0., G = 0., B = 0.;
+                int x2, y2, off = 4 * (y * w + x);
+
+                for(j = 0; j < n; j++)
+                {
+                    y2 = y + j - n / 2;
+                    if(y2 < 0) y2 = 0;
+                    else if(y2 >= h) y2 = h - 1;
+
+                    for(i = 0; i < m; i++)
+                    {
+                        double f = mat[j * m + i];
+
+                        x2 = x + i;
+                        if(x2 < 0) x2 = 0;
+                        else if(x2 >= w) x2 = w - 1;
+
+                        R += f * srcdata[(y * w + x2) * 4];
+                        G += f * srcdata[(y * w + x2) * 4 + 1];
+                        B += f * srcdata[(y * w + x2) * 4 + 2];
+                    }
+                }
+
+                dstdata[off] = R;
+                dstdata[off + 1] = G;
+                dstdata[off + 2] = B;
+            }
+        }
+    }
+
+    return dst;
+}
+
diff --git a/pipi/pipi.h b/pipi/pipi.h
index c942e58..1db03dd 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -73,6 +73,7 @@ extern double pipi_measure_rmsd(pipi_image_t *, pipi_image_t *);
 
 extern pipi_image_t *pipi_resize(pipi_image_t *, int, int);
 
+extern pipi_image_t *pipi_convolution(pipi_image_t *, int, int, double[]);
 extern pipi_image_t *pipi_gaussian_blur(pipi_image_t *, float);
 extern pipi_image_t *pipi_gaussian_blur_ext(pipi_image_t *,
                                             float, float, float, float);