[FFmpeg-devel] [PATCH] lavfi: edgedetect filter
Clément Bœsch
ubitux at gmail.com
Wed Aug 8 22:14:03 CEST 2012
On Wed, Aug 08, 2012 at 03:28:58PM +0200, Stefano Sabatini wrote:
[...]
> > > > +static void double_threshold(AVFilterContext *ctx, int w, int h,
> > > > + uint8_t *dst, int dst_linesize,
> > > > + const uint8_t *src, int src_linesize)
> > > > +{
> > > > + int i, j;
> > > > +
> > > > +#define THRES_HIGH 80
> > > > +#define THRES_LOW 20
> > >
> > > This values should be made parametric (and expressed as float values
> > > in the [0, 1] range).
> > >
> >
> > Yes, but right now the filter is called "edgedetect" and only implements
> > the canny algo. If we were to add more algo, we would end up with various
> > mode such as vf edgedetect=canny, or edgedetect=marrhildreth or such. So I
> > wasn't confident about making it customizable yet.
> >
> > This parametrization can be done later without breaking the usage, that
> > really was the main point.
>
> OK but this is trivial to implement, so I'd rather have this in the
> first version (without the need to add named options and stuff in a
> second commit).
>
> [...]
> > > Another consideration: we could optionally support faster less
> > > accurate algorithms (e.g. Marr-Hildreth).
> >
> > Feel free to implement it. I was just having fun with lavfi.
>
> Resume: threshold parametrization is trivial and should be added
> when pushing the first version.
>
> Gaussian mask sigma and size customization can be added later, same
> for generic convolution computation and for other edge detection
> algorithms with different features.
OK. New patch attached.
BTW, I don't really like that
av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
is being copied all over the place in the filters when
av_set_options_string() fails. Especially when the error is already
more than explicit and just clutters the output. Example:
[edgedetect @ 0x7f9468031ec0] [Eval @ 0x7f94749985b0] Invalid chars 'oo' at the end of expression '0.1foo'
[edgedetect @ 0x7f9468031ec0] Unable to parse option value "0.1foo"
[Parsed_edgedetect_2 @ 0x7f9468032f60] Error parsing options string: 'high=0.4:low=0.1foo'
Error initializing filter 'edgedetect' with args 'high=0.4:low=0.1foo'
There are 4 messages just to tell there is a syntax error. Sounds overkill
and redundant to me. Does anyone mind if I drop the mentioned av_log from
the filters?
--
Clément B.
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From 7ca50c30bc25f55a4cc5355597407a640b88f8a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Thu, 26 Jul 2012 19:45:53 +0200
Subject: [PATCH] lavfi: edgedetect filter
FIXME: bump lavfi minor
---
doc/filters.texi | 18 +++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_edgedetect.c | 324 ++++++++++++++++++++++++++++++++++++++++++++
tests/lavfi-regression.sh | 1 +
tests/ref/lavfi/edgedetect | 1 +
6 files changed, 346 insertions(+)
create mode 100644 libavfilter/vf_edgedetect.c
create mode 100644 tests/ref/lavfi/edgedetect
diff --git a/doc/filters.texi b/doc/filters.texi
index e73fc09..ec285c1 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1929,6 +1929,24 @@ For more information about libfreetype, check:
For more information about fontconfig, check:
@url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
+ at section edgedetect
+
+Detect and draw edges. The filter uses the Canny Edge Detection algorithm with
+the following optional named parameters:
+
+ at table @option
+ at item high
+Set high threshold. Default is @code{80/256}.
+
+ at item low
+Set low threshold. Default is @code{20/256}.
+ at end table
+
+Example:
+ at example
+edgedetect=low=0.1:high=0.4
+ at end example
+
@section fade
Apply fade-in/out effect to input video.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index b6bd37f..b8d89b0 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -89,6 +89,7 @@ OBJS-$(CONFIG_DELOGO_FILTER) += vf_delogo.o
OBJS-$(CONFIG_DESHAKE_FILTER) += vf_deshake.o
OBJS-$(CONFIG_DRAWBOX_FILTER) += vf_drawbox.o
OBJS-$(CONFIG_DRAWTEXT_FILTER) += vf_drawtext.o
+OBJS-$(CONFIG_EDGEDETECT_FILTER) += vf_edgedetect.o
OBJS-$(CONFIG_FADE_FILTER) += vf_fade.o
OBJS-$(CONFIG_FIELDORDER_FILTER) += vf_fieldorder.o
OBJS-$(CONFIG_FIFO_FILTER) += fifo.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index da1c8e6..91eec2a 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -79,6 +79,7 @@ void avfilter_register_all(void)
REGISTER_FILTER (DESHAKE, deshake, vf);
REGISTER_FILTER (DRAWBOX, drawbox, vf);
REGISTER_FILTER (DRAWTEXT, drawtext, vf);
+ REGISTER_FILTER (EDGEDETECT, edgedetect, vf);
REGISTER_FILTER (FADE, fade, vf);
REGISTER_FILTER (FIELDORDER, fieldorder, vf);
REGISTER_FILTER (FIFO, fifo, vf);
diff --git a/libavfilter/vf_edgedetect.c b/libavfilter/vf_edgedetect.c
new file mode 100644
index 0000000..1e25c2d
--- /dev/null
+++ b/libavfilter/vf_edgedetect.c
@@ -0,0 +1,324 @@
+/*
+ * Copyright (c) 2012 Clément Bœsch
+ *
+ * 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
+ * Edge detection filter
+ *
+ * @url https://en.wikipedia.org/wiki/Canny_edge_detector
+ */
+
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct {
+ const AVClass *class;
+ uint8_t *tmpbuf;
+ uint16_t *gradients;
+ char *directions;
+ double lowd, highd;
+ uint8_t low, high;
+} EdgeDetectContext;
+
+#define OFFSET(x) offsetof(EdgeDetectContext, x)
+static const AVOption edgedetect_options[] = {
+ { "high", "set high threshold", OFFSET(highd), AV_OPT_TYPE_DOUBLE, {.dbl=80/256.}, 0, 1 },
+ { "low", "set low threshold", OFFSET(lowd), AV_OPT_TYPE_DOUBLE, {.dbl=20/256.}, 0, 1 },
+ { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(edgedetect);
+
+static av_cold int init(AVFilterContext *ctx, const char *args)
+{
+ int ret;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ edgedetect->class = &edgedetect_class;
+ av_opt_set_defaults(edgedetect);
+
+ if ((ret = av_set_options_string(edgedetect, args, "=", ":")) < 0) {
+ av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
+ return ret;
+ }
+
+ edgedetect->low = edgedetect->lowd * 256.;
+ edgedetect->high = edgedetect->highd * 256.;
+ return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ static const enum PixelFormat pix_fmts[] = {PIX_FMT_GRAY8, PIX_FMT_NONE};
+ ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+ return 0;
+}
+
+static int config_props(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ edgedetect->tmpbuf = av_malloc(inlink->w * inlink->h);
+ edgedetect->gradients = av_calloc(inlink->w * inlink->h, sizeof(*edgedetect->gradients));
+ edgedetect->directions = av_malloc(inlink->w * inlink->h);
+ if (!edgedetect->tmpbuf || !edgedetect->gradients || !edgedetect->directions)
+ return AVERROR(ENOMEM);
+ 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;
+ 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++) {
+ 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);
+}
+
+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 arith:
+ * 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 <<= 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(AVFilterContext *ctx, int w, int h,
+ uint16_t *dst, int dst_linesize,
+ const uint8_t *src, int src_linesize)
+{
+ int i, j;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ for (j = 1; j < h - 1; j++) {
+ dst += dst_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);
+ edgedetect->directions[j*w + i] = get_rounded_direction(gx, gy);
+ }
+ }
+}
+
+static void non_maximum_suppression(AVFilterContext *ctx, int w, int h,
+ uint8_t *dst, int dst_linesize,
+ const uint16_t *src, int src_linesize)
+{
+ int i, j;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+#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;
+ src += src_linesize;
+ for (i = 1; i < w - 1; i++) {
+ switch (edgedetect->directions[j*w + 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(AVFilterContext *ctx, int w, int h,
+ uint8_t *dst, int dst_linesize,
+ const uint8_t *src, int src_linesize)
+{
+ int i, j;
+ EdgeDetectContext *edgedetect = ctx->priv;
+ const int low = edgedetect->low;
+ const int high = edgedetect->high;
+
+ 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 int end_frame(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ EdgeDetectContext *edgedetect = ctx->priv;
+ AVFilterLink *outlink = inlink->dst->outputs[0];
+ AVFilterBufferRef *inpicref = inlink->cur_buf;
+ AVFilterBufferRef *outpicref = outlink->out_buf;
+ uint8_t *tmpbuf = edgedetect->tmpbuf;
+ uint16_t *gradients = edgedetect->gradients;
+
+ /* gaussian filter to reduce noise */
+ gaussian_blur(ctx, inlink->w, inlink->h,
+ tmpbuf, inlink->w,
+ inpicref->data[0], inpicref->linesize[0]);
+
+ /* compute the 16-bits gradients and directions for the next step */
+ sobel(ctx, inlink->w, inlink->h,
+ gradients, inlink->w,
+ tmpbuf, inlink->w);
+
+ /* non_maximum_suppression() will actually keep & clip what's necessary and
+ * ignore the rest, so we need a clean output buffer */
+ memset(tmpbuf, 0, inlink->w * inlink->h);
+ non_maximum_suppression(ctx, inlink->w, inlink->h,
+ tmpbuf, inlink->w,
+ gradients, inlink->w);
+
+ /* keep high values, or low values surrounded by high values */
+ double_threshold(ctx, inlink->w, inlink->h,
+ outpicref->data[0], outpicref->linesize[0],
+ tmpbuf, inlink->w);
+
+ ff_draw_slice(outlink, 0, outlink->h, 1);
+ return ff_end_frame(outlink);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+ EdgeDetectContext *edgedetect = ctx->priv;
+ av_freep(&edgedetect->tmpbuf);
+ av_freep(&edgedetect->gradients);
+ av_freep(&edgedetect->directions);
+}
+
+static int null_draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir) { return 0; }
+
+AVFilter avfilter_vf_edgedetect = {
+ .name = "edgedetect",
+ .description = NULL_IF_CONFIG_SMALL("Detect and draw edge."),
+ .priv_size = sizeof(EdgeDetectContext),
+ .init = init,
+ .uninit = uninit,
+ .query_formats = query_formats,
+
+ .inputs = (const AVFilterPad[]) {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .draw_slice = null_draw_slice,
+ .config_props = config_props,
+ .end_frame = end_frame,
+ .min_perms = AV_PERM_READ
+ },
+ { .name = NULL }
+ },
+ .outputs = (const AVFilterPad[]) {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ { .name = NULL }
+ },
+};
diff --git a/tests/lavfi-regression.sh b/tests/lavfi-regression.sh
index c763e99..0496d8a 100755
--- a/tests/lavfi-regression.sh
+++ b/tests/lavfi-regression.sh
@@ -42,6 +42,7 @@ do_lavfi "crop_scale" "crop=iw-100:ih-100:100:100,scale=400:-1"
do_lavfi "crop_scale_vflip" "null,null,crop=iw-200:ih-200:200:200,crop=iw-20:ih-20:20:20,scale=200:200,scale=250:250,vflip,vflip,null,scale=200:200,crop=iw-100:ih-100:100:100,vflip,scale=200:200,null,vflip,crop=iw-100:ih-100:100:100,null"
do_lavfi "crop_vflip" "crop=iw-100:ih-100:100:100,vflip"
do_lavfi "drawbox" "drawbox=224:24:88:72:#FF8010 at 0.5"
+do_lavfi "edgedetect" "edgedetect"
do_lavfi "fade" "fade=in:5:15,fade=out:30:15"
do_lavfi "null" "null"
do_lavfi "overlay" "split[m],scale=88:72,pad=96:80:4:4[o2];[m]fifo[o1],[o1][o2]overlay=240:16"
diff --git a/tests/ref/lavfi/edgedetect b/tests/ref/lavfi/edgedetect
new file mode 100644
index 0000000..52bae0b
--- /dev/null
+++ b/tests/ref/lavfi/edgedetect
@@ -0,0 +1 @@
+edgedetect 8fbed1b56636619f3b2d8d7b221c9242
--
1.7.11.4
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