diff options
Diffstat (limited to 'libavfilter/vf_edgedetect.c')
-rw-r--r-- | libavfilter/vf_edgedetect.c | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/libavfilter/vf_edgedetect.c b/libavfilter/vf_edgedetect.c new file mode 100644 index 0000000000..ac88e02a11 --- /dev/null +++ b/libavfilter/vf_edgedetect.c @@ -0,0 +1,399 @@ +/* + * 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; + int 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; + static const enum AVPixelFormat wires_pix_fmts[] = {AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE}; + static const enum AVPixelFormat colormix_pix_fmts[] = {AV_PIX_FMT_GBRP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE}; + AVFilterFormats *fmts_list; + const enum AVPixelFormat *pix_fmts = NULL; + + if (edgedetect->mode == MODE_WIRES) { + pix_fmts = wires_pix_fmts; + } else if (edgedetect->mode == MODE_COLORMIX) { + pix_fmts = colormix_pix_fmts; + } else { + av_assert0(0); + } + fmts_list = ff_make_format_list(pix_fmts); + if (!fmts_list) + return AVERROR(ENOMEM); + return ff_set_common_formats(ctx, fmts_list); +} + +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, +}; 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