| /* |
| * 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, |
| }; |