summaryrefslogtreecommitdiff
path: root/libavfilter/vf_edgedetect.c
diff options
context:
space:
mode:
Diffstat (limited to 'libavfilter/vf_edgedetect.c')
-rw-r--r--libavfilter/vf_edgedetect.c394
1 files changed, 394 insertions, 0 deletions
diff --git a/libavfilter/vf_edgedetect.c b/libavfilter/vf_edgedetect.c
new file mode 100644
index 0000000000..7316412edd
--- /dev/null
+++ b/libavfilter/vf_edgedetect.c
@@ -0,0 +1,394 @@
+/*
+ * Copyright (c) 2012-2014 Clément Bœsch <u pkh me>
+ *
+ * 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
+ *
+ * @see https://en.wikipedia.org/wiki/Canny_edge_detector
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+enum FilterMode {
+ MODE_WIRES,
+ MODE_COLORMIX,
+ NB_MODE
+};
+
+struct plane_info {
+ uint8_t *tmpbuf;
+ uint16_t *gradients;
+ char *directions;
+};
+
+typedef struct {
+ const AVClass *class;
+ struct plane_info planes[3];
+ int nb_planes;
+ double low, high;
+ uint8_t low_u8, high_u8;
+ enum FilterMode mode;
+} EdgeDetectContext;
+
+#define OFFSET(x) offsetof(EdgeDetectContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption edgedetect_options[] = {
+ { "high", "set high threshold", OFFSET(high), AV_OPT_TYPE_DOUBLE, {.dbl=50/255.}, 0, 1, FLAGS },
+ { "low", "set low threshold", OFFSET(low), AV_OPT_TYPE_DOUBLE, {.dbl=20/255.}, 0, 1, FLAGS },
+ { "mode", "set mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_WIRES}, 0, NB_MODE-1, FLAGS, "mode" },
+ { "wires", "white/gray wires on black", 0, AV_OPT_TYPE_CONST, {.i64=MODE_WIRES}, INT_MIN, INT_MAX, FLAGS, "mode" },
+ { "colormix", "mix colors", 0, AV_OPT_TYPE_CONST, {.i64=MODE_COLORMIX}, INT_MIN, INT_MAX, FLAGS, "mode" },
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(edgedetect);
+
+static av_cold int init(AVFilterContext *ctx)
+{
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ edgedetect->low_u8 = edgedetect->low * 255. + .5;
+ edgedetect->high_u8 = edgedetect->high * 255. + .5;
+ return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ const EdgeDetectContext *edgedetect = ctx->priv;
+
+ if (edgedetect->mode == MODE_WIRES) {
+ static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE};
+ ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+ } else if (edgedetect->mode == MODE_COLORMIX) {
+ static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_GBRP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE};
+ ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+ } else {
+ av_assert0(0);
+ }
+ return 0;
+}
+
+static int config_props(AVFilterLink *inlink)
+{
+ int p;
+ AVFilterContext *ctx = inlink->dst;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ edgedetect->nb_planes = inlink->format == AV_PIX_FMT_GRAY8 ? 1 : 3;
+ for (p = 0; p < edgedetect->nb_planes; p++) {
+ struct plane_info *plane = &edgedetect->planes[p];
+
+ plane->tmpbuf = av_malloc(inlink->w * inlink->h);
+ plane->gradients = av_calloc(inlink->w * inlink->h, sizeof(*plane->gradients));
+ plane->directions = av_malloc(inlink->w * inlink->h);
+ if (!plane->tmpbuf || !plane->gradients || !plane->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++) {
+ /* 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);
+}
+
+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 <<= 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)
+{
+ int i, j;
+
+ for (j = 0; j < h; j++) {
+ for (i = 0; i < w; i++)
+ dst[i] = (dst[i] + src[i]) >> 1;
+ dst += dst_linesize;
+ src += src_linesize;
+ }
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+ AVFilterContext *ctx = inlink->dst;
+ EdgeDetectContext *edgedetect = ctx->priv;
+ AVFilterLink *outlink = ctx->outputs[0];
+ int p, direct = 0;
+ AVFrame *out;
+
+ if (edgedetect->mode != MODE_COLORMIX && av_frame_is_writable(in)) {
+ direct = 1;
+ out = in;
+ } else {
+ out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+ if (!out) {
+ av_frame_free(&in);
+ return AVERROR(ENOMEM);
+ }
+ av_frame_copy_props(out, in);
+ }
+
+ for (p = 0; p < edgedetect->nb_planes; p++) {
+ struct plane_info *plane = &edgedetect->planes[p];
+ uint8_t *tmpbuf = plane->tmpbuf;
+ uint16_t *gradients = plane->gradients;
+ int8_t *directions = plane->directions;
+
+ /* gaussian filter to reduce noise */
+ gaussian_blur(ctx, inlink->w, inlink->h,
+ tmpbuf, inlink->w,
+ in->data[p], in->linesize[p]);
+
+ /* compute the 16-bits gradients and directions for the next step */
+ sobel(inlink->w, inlink->h,
+ gradients, inlink->w,
+ directions,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(inlink->w, inlink->h,
+ tmpbuf, inlink->w,
+ directions,inlink->w,
+ gradients, inlink->w);
+
+ /* keep high values, or low values surrounded by high values */
+ double_threshold(edgedetect->low_u8, edgedetect->high_u8,
+ inlink->w, inlink->h,
+ out->data[p], out->linesize[p],
+ tmpbuf, inlink->w);
+
+ if (edgedetect->mode == MODE_COLORMIX) {
+ color_mix(inlink->w, inlink->h,
+ out->data[p], out->linesize[p],
+ in->data[p], in->linesize[p]);
+ }
+ }
+
+ if (!direct)
+ av_frame_free(&in);
+ return ff_filter_frame(outlink, out);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+ int p;
+ EdgeDetectContext *edgedetect = ctx->priv;
+
+ for (p = 0; p < edgedetect->nb_planes; p++) {
+ struct plane_info *plane = &edgedetect->planes[p];
+ av_freep(&plane->tmpbuf);
+ av_freep(&plane->gradients);
+ av_freep(&plane->directions);
+ }
+}
+
+static const AVFilterPad edgedetect_inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .config_props = config_props,
+ .filter_frame = filter_frame,
+ },
+ { NULL }
+};
+
+static const AVFilterPad edgedetect_outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ { NULL }
+};
+
+AVFilter ff_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 = edgedetect_inputs,
+ .outputs = edgedetect_outputs,
+ .priv_class = &edgedetect_class,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+};
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-10 05:33:15 +0000