diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 08edc92d8c..1b559539ba 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -258,7 +258,7 @@ OBJS-$(CONFIG_DRAWBOX_FILTER)                += vf_drawbox.o
 OBJS-$(CONFIG_DRAWGRAPH_FILTER)              += f_drawgraph.o
 OBJS-$(CONFIG_DRAWGRID_FILTER)               += vf_drawbox.o
 OBJS-$(CONFIG_DRAWTEXT_FILTER)               += vf_drawtext.o
-OBJS-$(CONFIG_EDGEDETECT_FILTER)             += vf_edgedetect.o
+OBJS-$(CONFIG_EDGEDETECT_FILTER)             += vf_edgedetect.o edge_common.o
 OBJS-$(CONFIG_ELBG_FILTER)                   += vf_elbg.o
 OBJS-$(CONFIG_ENTROPY_FILTER)                += vf_entropy.o
 OBJS-$(CONFIG_EPX_FILTER)                    += vf_epx.o
diff --git a/libavfilter/edge_common.c b/libavfilter/edge_common.c
new file mode 100644
index 0000000000..d72e8521cd
--- /dev/null
+++ b/libavfilter/edge_common.c
@@ -0,0 +1,181 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "edge_common.h"
+
+// Internal helper for ff_sobel()
+static int get_rounded_direction(int gx, int gy)
+{
+    /* reference angles:
+     *   tan( pi/8) = sqrt(2)-1
+     *   tan(3pi/8) = sqrt(2)+1
+     * Gy/Gx is the tangent of the angle (theta), so Gy/Gx is compared against
+     * <ref-angle>, or more simply Gy against <ref-angle>*Gx
+     *
+     * Gx and Gy bounds = [-1020;1020], using 16-bit arithmetic:
+     *   round((sqrt(2)-1) * (1<<16)) =  27146
+     *   round((sqrt(2)+1) * (1<<16)) = 158218
+     */
+    if (gx) {
+        int tanpi8gx, tan3pi8gx;
+
+        if (gx < 0)
+            gx = -gx, gy = -gy;
+        gy *= (1 << 16);
+        tanpi8gx  =  27146 * gx;
+        tan3pi8gx = 158218 * gx;
+        if (gy > -tan3pi8gx && gy < -tanpi8gx)  return DIRECTION_45UP;
+        if (gy > -tanpi8gx  && gy <  tanpi8gx)  return DIRECTION_HORIZONTAL;
+        if (gy >  tanpi8gx  && gy <  tan3pi8gx) return DIRECTION_45DOWN;
+    }
+    return DIRECTION_VERTICAL;
+}
+
+// Simple sobel operator to get rounded gradients
+void ff_sobel(int w, int h,
+                    uint16_t *dst, int dst_linesize,
+                    int8_t *dir, int dir_linesize,
+                    const uint8_t *src, int src_linesize)
+{
+    int i, j;
+
+    for (j = 1; j < h - 1; j++) {
+        dst += dst_linesize;
+        dir += dir_linesize;
+        src += src_linesize;
+        for (i = 1; i < w - 1; i++) {
+            const int gx =
+                -1*src[-src_linesize + i-1] + 1*src[-src_linesize + i+1]
+                -2*src[                i-1] + 2*src[                i+1]
+                -1*src[ src_linesize + i-1] + 1*src[ src_linesize + i+1];
+            const int gy =
+                -1*src[-src_linesize + i-1] + 1*src[ src_linesize + i-1]
+                -2*src[-src_linesize + i  ] + 2*src[ src_linesize + i  ]
+                -1*src[-src_linesize + i+1] + 1*src[ src_linesize + i+1];
+
+            dst[i] = FFABS(gx) + FFABS(gy);
+            dir[i] = get_rounded_direction(gx, gy);
+        }
+    }
+}
+
+// Filters rounded gradients to drop all non-maxima
+// Expects gradients generated by ff_sobel()
+// Expects zero's destination buffer
+void ff_non_maximum_suppression(int w, int h,
+                                      uint8_t *dst, int dst_linesize,
+                                      const int8_t *dir, int dir_linesize,
+                                      const uint16_t *src, int src_linesize)
+{
+    int i, j;
+
+#define COPY_MAXIMA(ay, ax, by, bx) do {                \
+    if (src[i] > src[(ay)*src_linesize + i+(ax)] &&     \
+        src[i] > src[(by)*src_linesize + i+(bx)])       \
+        dst[i] = av_clip_uint8(src[i]);                 \
+} while (0)
+
+    for (j = 1; j < h - 1; j++) {
+        dst += dst_linesize;
+        dir += dir_linesize;
+        src += src_linesize;
+        for (i = 1; i < w - 1; i++) {
+            switch (dir[i]) {
+            case DIRECTION_45UP:        COPY_MAXIMA( 1, -1, -1,  1); break;
+            case DIRECTION_45DOWN:      COPY_MAXIMA(-1, -1,  1,  1); break;
+            case DIRECTION_HORIZONTAL:  COPY_MAXIMA( 0, -1,  0,  1); break;
+            case DIRECTION_VERTICAL:    COPY_MAXIMA(-1,  0,  1,  0); break;
+            }
+        }
+    }
+}
+
+// Filter to keep all pixels > high, and keep all pixels > low where all surrounding pixels > high
+void ff_double_threshold(int low, int high, int w, int h,
+                               uint8_t *dst, int dst_linesize,
+                               const uint8_t *src, int src_linesize)
+{
+    int i, j;
+
+    for (j = 0; j < h; j++) {
+        for (i = 0; i < w; i++) {
+            if (src[i] > high) {
+                dst[i] = src[i];
+                continue;
+            }
+
+            if (!(!i || i == w - 1 || !j || j == h - 1) &&
+                src[i] > low &&
+                (src[-src_linesize + i-1] > high ||
+                 src[-src_linesize + i  ] > high ||
+                 src[-src_linesize + i+1] > high ||
+                 src[                i-1] > high ||
+                 src[                i+1] > high ||
+                 src[ src_linesize + i-1] > high ||
+                 src[ src_linesize + i  ] > high ||
+                 src[ src_linesize + i+1] > high))
+                dst[i] = src[i];
+            else
+                dst[i] = 0;
+        }
+        dst += dst_linesize;
+        src += src_linesize;
+    }
+}
+
+// Applies gaussian blur, using 5x5 kernels, sigma = 1.4
+void ff_gaussian_blur(int w, int h,
+                      uint8_t *dst, int dst_linesize,
+                      const uint8_t *src, int src_linesize)
+{
+    int i, j;
+
+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
+    for (j = 2; j < h - 2; j++) {
+        dst[0] = src[0];
+        dst[1] = src[1];
+        for (i = 2; i < w - 2; i++) {
+            /* Gaussian mask of size 5x5 with sigma = 1.4 */
+            dst[i] = ((src[-2*src_linesize + i-2] + src[2*src_linesize + i-2]) * 2
+                    + (src[-2*src_linesize + i-1] + src[2*src_linesize + i-1]) * 4
+                    + (src[-2*src_linesize + i  ] + src[2*src_linesize + i  ]) * 5
+                    + (src[-2*src_linesize + i+1] + src[2*src_linesize + i+1]) * 4
+                    + (src[-2*src_linesize + i+2] + src[2*src_linesize + i+2]) * 2
+
+                    + (src[  -src_linesize + i-2] + src[  src_linesize + i-2]) *  4
+                    + (src[  -src_linesize + i-1] + src[  src_linesize + i-1]) *  9
+                    + (src[  -src_linesize + i  ] + src[  src_linesize + i  ]) * 12
+                    + (src[  -src_linesize + i+1] + src[  src_linesize + i+1]) *  9
+                    + (src[  -src_linesize + i+2] + src[  src_linesize + i+2]) *  4
+
+                    + src[i-2] *  5
+                    + src[i-1] * 12
+                    + src[i  ] * 15
+                    + src[i+1] * 12
+                    + src[i+2] *  5) / 159;
+        }
+        dst[i    ] = src[i    ];
+        dst[i + 1] = src[i + 1];
+
+        dst += dst_linesize;
+        src += src_linesize;
+    }
+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
+    memcpy(dst, src, w);
+}
diff --git a/libavfilter/edge_common.h b/libavfilter/edge_common.h
new file mode 100644
index 0000000000..87c143f2b8
--- /dev/null
+++ b/libavfilter/edge_common.h
@@ -0,0 +1,107 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * common functions for edge detection
+ */
+
+#ifndef AVFILTER_EDGE_COMMON_H
+#define AVFILTER_EDGE_COMMON_H
+
+#include "avfilter.h"
+
+/**
+ * @brief Rounded directions used in av_image_sobel()
+ */
+enum AVRoundedDirection {
+    DIRECTION_45UP,
+    DIRECTION_45DOWN,
+    DIRECTION_HORIZONTAL,
+    DIRECTION_VERTICAL,
+};
+
+/**
+ * Simple sobel operator to get rounded gradients
+ *
+ * @param w             the width of the image in pixels
+ * @param h             the height of the image in pixels
+ * @param dst           data pointers to magnitude image
+ * @param dst_linesize  linesizes for the magnitude image
+ * @param dir           data pointers to direction image
+ * @param dir_linesize  linesizes for the direction image
+ * @param src           data pointers to source image
+ * @param src_linesize  linesizes for the source image
+ */
+void ff_sobel(int w, int h,
+              uint16_t *dst, int dst_linesize,
+              int8_t *dir, int dir_linesize,
+              const uint8_t *src, int src_linesize);
+
+/**
+ * Filters rounded gradients to drop all non-maxima pixels in the magnitude image
+ * Expects gradients generated by av_image_sobel()
+ * Expects zero's in the destination buffer dst
+ *
+ * @param w             the width of the image in pixels
+ * @param h             the height of the image in pixels
+ * @param dst           data pointers to magnitude image
+ * @param dst_linesize  linesizes for the magnitude image
+ * @param dir           data pointers to direction image
+ * @param dir_linesize  linesizes for the direction image
+ * @param src           data pointers to source image
+ * @param src_linesize  linesizes for the source image
+ */
+void ff_non_maximum_suppression(int w, int h,
+                                uint8_t *dst, int dst_linesize,
+                                const int8_t *dir, int dir_linesize,
+                                const uint16_t *src, int src_linesize);
+
+/**
+ * Filters all pixels in src to keep all pixels > high,
+ * and keep all pixels > low where all surrounding pixels > high
+ *
+ * @param low           the low threshold value
+ * @param high          the hegh threshold value
+ * @param w             the width of the image in pixels
+ * @param h             the height of the image in pixels
+ * @param dst           data pointers to destination image
+ * @param dst_linesize  linesizes for the destination image
+ * @param src           data pointers to source image
+ * @param src_linesize  linesizes for the source image
+ */
+void ff_double_threshold(int low, int high, int w, int h,
+                         uint8_t *dst, int dst_linesize,
+                         const uint8_t *src, int src_linesize);
+
+/**
+ * Applies gaussian blur.
+ * 5x5 kernels, sigma = 1.4
+ *
+ * @param w             the width of the image in pixels
+ * @param h             the height of the image in pixels
+ * @param dst           data pointers to destination image
+ * @param dst_linesize  linesizes for the destination image
+ * @param src           data pointers to source image
+ * @param src_linesize  linesizes for the source image
+ */
+void ff_gaussian_blur(int w, int h,
+                      uint8_t *dst, int dst_linesize,
+                      const uint8_t *src, int src_linesize);
+
+#endif
diff --git a/libavfilter/vf_edgedetect.c b/libavfilter/vf_edgedetect.c
index 3eea34e325..90390ceb3e 100644
--- a/libavfilter/vf_edgedetect.c
+++ b/libavfilter/vf_edgedetect.c
@@ -32,6 +32,7 @@
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
+#include "edge_common.h"
 
 #define PLANE_R 0x4
 #define PLANE_G 0x1
@@ -139,176 +140,6 @@ static int config_props(AVFilterLink *inlink)
     return 0;
 }
 
-static void gaussian_blur(AVFilterContext *ctx, int w, int h,
-                                uint8_t *dst, int dst_linesize,
-                          const uint8_t *src, int src_linesize)
-{
-    int i, j;
-
-    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
-    if (h > 1) {
-        memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
-    }
-    for (j = 2; j < h - 2; j++) {
-        dst[0] = src[0];
-        if (w > 1)
-            dst[1] = src[1];
-        for (i = 2; i < w - 2; i++) {
-            /* Gaussian mask of size 5x5 with sigma = 1.4 */
-            dst[i] = ((src[-2*src_linesize + i-2] + src[2*src_linesize + i-2]) * 2
-                    + (src[-2*src_linesize + i-1] + src[2*src_linesize + i-1]) * 4
-                    + (src[-2*src_linesize + i  ] + src[2*src_linesize + i  ]) * 5
-                    + (src[-2*src_linesize + i+1] + src[2*src_linesize + i+1]) * 4
-                    + (src[-2*src_linesize + i+2] + src[2*src_linesize + i+2]) * 2
-
-                    + (src[  -src_linesize + i-2] + src[  src_linesize + i-2]) *  4
-                    + (src[  -src_linesize + i-1] + src[  src_linesize + i-1]) *  9
-                    + (src[  -src_linesize + i  ] + src[  src_linesize + i  ]) * 12
-                    + (src[  -src_linesize + i+1] + src[  src_linesize + i+1]) *  9
-                    + (src[  -src_linesize + i+2] + src[  src_linesize + i+2]) *  4
-
-                    + src[i-2] *  5
-                    + src[i-1] * 12
-                    + src[i  ] * 15
-                    + src[i+1] * 12
-                    + src[i+2] *  5) / 159;
-        }
-        if (w > 2)
-            dst[i    ] = src[i    ];
-        if (w > 3)
-            dst[i + 1] = src[i + 1];
-
-        dst += dst_linesize;
-        src += src_linesize;
-    }
-    if (h > 2) {
-        memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;
-    }
-    if (h > 3)
-        memcpy(dst, src, w);
-}
-
-enum {
-    DIRECTION_45UP,
-    DIRECTION_45DOWN,
-    DIRECTION_HORIZONTAL,
-    DIRECTION_VERTICAL,
-};
-
-static int get_rounded_direction(int gx, int gy)
-{
-    /* reference angles:
-     *   tan( pi/8) = sqrt(2)-1
-     *   tan(3pi/8) = sqrt(2)+1
-     * Gy/Gx is the tangent of the angle (theta), so Gy/Gx is compared against
-     * <ref-angle>, or more simply Gy against <ref-angle>*Gx
-     *
-     * Gx and Gy bounds = [-1020;1020], using 16-bit arithmetic:
-     *   round((sqrt(2)-1) * (1<<16)) =  27146
-     *   round((sqrt(2)+1) * (1<<16)) = 158218
-     */
-    if (gx) {
-        int tanpi8gx, tan3pi8gx;
-
-        if (gx < 0)
-            gx = -gx, gy = -gy;
-        gy *= (1 << 16);
-        tanpi8gx  =  27146 * gx;
-        tan3pi8gx = 158218 * gx;
-        if (gy > -tan3pi8gx && gy < -tanpi8gx)  return DIRECTION_45UP;
-        if (gy > -tanpi8gx  && gy <  tanpi8gx)  return DIRECTION_HORIZONTAL;
-        if (gy >  tanpi8gx  && gy <  tan3pi8gx) return DIRECTION_45DOWN;
-    }
-    return DIRECTION_VERTICAL;
-}
-
-static void sobel(int w, int h,
-                       uint16_t *dst, int dst_linesize,
-                         int8_t *dir, int dir_linesize,
-                  const uint8_t *src, int src_linesize)
-{
-    int i, j;
-
-    for (j = 1; j < h - 1; j++) {
-        dst += dst_linesize;
-        dir += dir_linesize;
-        src += src_linesize;
-        for (i = 1; i < w - 1; i++) {
-            const int gx =
-                -1*src[-src_linesize + i-1] + 1*src[-src_linesize + i+1]
-                -2*src[                i-1] + 2*src[                i+1]
-                -1*src[ src_linesize + i-1] + 1*src[ src_linesize + i+1];
-            const int gy =
-                -1*src[-src_linesize + i-1] + 1*src[ src_linesize + i-1]
-                -2*src[-src_linesize + i  ] + 2*src[ src_linesize + i  ]
-                -1*src[-src_linesize + i+1] + 1*src[ src_linesize + i+1];
-
-            dst[i] = FFABS(gx) + FFABS(gy);
-            dir[i] = get_rounded_direction(gx, gy);
-        }
-    }
-}
-
-static void non_maximum_suppression(int w, int h,
-                                          uint8_t  *dst, int dst_linesize,
-                                    const  int8_t  *dir, int dir_linesize,
-                                    const uint16_t *src, int src_linesize)
-{
-    int i, j;
-
-#define COPY_MAXIMA(ay, ax, by, bx) do {                \
-    if (src[i] > src[(ay)*src_linesize + i+(ax)] &&     \
-        src[i] > src[(by)*src_linesize + i+(bx)])       \
-        dst[i] = av_clip_uint8(src[i]);                 \
-} while (0)
-
-    for (j = 1; j < h - 1; j++) {
-        dst += dst_linesize;
-        dir += dir_linesize;
-        src += src_linesize;
-        for (i = 1; i < w - 1; i++) {
-            switch (dir[i]) {
-            case DIRECTION_45UP:        COPY_MAXIMA( 1, -1, -1,  1); break;
-            case DIRECTION_45DOWN:      COPY_MAXIMA(-1, -1,  1,  1); break;
-            case DIRECTION_HORIZONTAL:  COPY_MAXIMA( 0, -1,  0,  1); break;
-            case DIRECTION_VERTICAL:    COPY_MAXIMA(-1,  0,  1,  0); break;
-            }
-        }
-    }
-}
-
-static void double_threshold(int low, int high, int w, int h,
-                                   uint8_t *dst, int dst_linesize,
-                             const uint8_t *src, int src_linesize)
-{
-    int i, j;
-
-    for (j = 0; j < h; j++) {
-        for (i = 0; i < w; i++) {
-            if (src[i] > high) {
-                dst[i] = src[i];
-                continue;
-            }
-
-            if (!(!i || i == w - 1 || !j || j == h - 1) &&
-                src[i] > low &&
-                (src[-src_linesize + i-1] > high ||
-                 src[-src_linesize + i  ] > high ||
-                 src[-src_linesize + i+1] > high ||
-                 src[                i-1] > high ||
-                 src[                i+1] > high ||
-                 src[ src_linesize + i-1] > high ||
-                 src[ src_linesize + i  ] > high ||
-                 src[ src_linesize + i+1] > high))
-                dst[i] = src[i];
-            else
-                dst[i] = 0;
-        }
-        dst += dst_linesize;
-        src += src_linesize;
-    }
-}
-
 static void color_mix(int w, int h,
                             uint8_t *dst, int dst_linesize,
                       const uint8_t *src, int src_linesize)
@@ -360,12 +191,12 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         }
 
         /* gaussian filter to reduce noise  */
-        gaussian_blur(ctx, width, height,
-                      tmpbuf,      width,
-                      in->data[p], in->linesize[p]);
+        ff_gaussian_blur(width, height,
+                         tmpbuf,      width,
+                         in->data[p], in->linesize[p]);
 
         /* compute the 16-bits gradients and directions for the next step */
-        sobel(width, height,
+        ff_sobel(width, height,
               gradients, width,
               directions,width,
               tmpbuf,    width);
@@ -373,13 +204,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         /* non_maximum_suppression() will actually keep & clip what's necessary and
          * ignore the rest, so we need a clean output buffer */
         memset(tmpbuf, 0, width * height);
-        non_maximum_suppression(width, height,
+        ff_non_maximum_suppression(width, height,
                                 tmpbuf,    width,
                                 directions,width,
                                 gradients, width);
 
         /* keep high values, or low values surrounded by high values */
-        double_threshold(edgedetect->low_u8, edgedetect->high_u8,
+        ff_double_threshold(edgedetect->low_u8, edgedetect->high_u8,
                          width, height,
                          out->data[p], out->linesize[p],
                          tmpbuf,       width);
