| 1 | /* |
| 2 | * Copyright (c) 2012-2014 Clément Bœsch <u pkh me> |
| 3 | * |
| 4 | * This file is part of FFmpeg. |
| 5 | * |
| 6 | * FFmpeg is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * FFmpeg is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with FFmpeg; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | */ |
| 20 | |
| 21 | /** |
| 22 | * @file |
| 23 | * Edge detection filter |
| 24 | * |
| 25 | * @see https://en.wikipedia.org/wiki/Canny_edge_detector |
| 26 | */ |
| 27 | |
| 28 | #include "libavutil/avassert.h" |
| 29 | #include "libavutil/opt.h" |
| 30 | #include "avfilter.h" |
| 31 | #include "formats.h" |
| 32 | #include "internal.h" |
| 33 | #include "video.h" |
| 34 | |
| 35 | enum FilterMode { |
| 36 | MODE_WIRES, |
| 37 | MODE_COLORMIX, |
| 38 | NB_MODE |
| 39 | }; |
| 40 | |
| 41 | struct plane_info { |
| 42 | uint8_t *tmpbuf; |
| 43 | uint16_t *gradients; |
| 44 | char *directions; |
| 45 | }; |
| 46 | |
| 47 | typedef struct { |
| 48 | const AVClass *class; |
| 49 | struct plane_info planes[3]; |
| 50 | int nb_planes; |
| 51 | double low, high; |
| 52 | uint8_t low_u8, high_u8; |
| 53 | enum FilterMode mode; |
| 54 | } EdgeDetectContext; |
| 55 | |
| 56 | #define OFFSET(x) offsetof(EdgeDetectContext, x) |
| 57 | #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM |
| 58 | static const AVOption edgedetect_options[] = { |
| 59 | { "high", "set high threshold", OFFSET(high), AV_OPT_TYPE_DOUBLE, {.dbl=50/255.}, 0, 1, FLAGS }, |
| 60 | { "low", "set low threshold", OFFSET(low), AV_OPT_TYPE_DOUBLE, {.dbl=20/255.}, 0, 1, FLAGS }, |
| 61 | { "mode", "set mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_WIRES}, 0, NB_MODE-1, FLAGS, "mode" }, |
| 62 | { "wires", "white/gray wires on black", 0, AV_OPT_TYPE_CONST, {.i64=MODE_WIRES}, INT_MIN, INT_MAX, FLAGS, "mode" }, |
| 63 | { "colormix", "mix colors", 0, AV_OPT_TYPE_CONST, {.i64=MODE_COLORMIX}, INT_MIN, INT_MAX, FLAGS, "mode" }, |
| 64 | { NULL } |
| 65 | }; |
| 66 | |
| 67 | AVFILTER_DEFINE_CLASS(edgedetect); |
| 68 | |
| 69 | static av_cold int init(AVFilterContext *ctx) |
| 70 | { |
| 71 | EdgeDetectContext *edgedetect = ctx->priv; |
| 72 | |
| 73 | edgedetect->low_u8 = edgedetect->low * 255. + .5; |
| 74 | edgedetect->high_u8 = edgedetect->high * 255. + .5; |
| 75 | return 0; |
| 76 | } |
| 77 | |
| 78 | static int query_formats(AVFilterContext *ctx) |
| 79 | { |
| 80 | const EdgeDetectContext *edgedetect = ctx->priv; |
| 81 | |
| 82 | if (edgedetect->mode == MODE_WIRES) { |
| 83 | static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE}; |
| 84 | ff_set_common_formats(ctx, ff_make_format_list(pix_fmts)); |
| 85 | } else if (edgedetect->mode == MODE_COLORMIX) { |
| 86 | static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_GBRP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE}; |
| 87 | ff_set_common_formats(ctx, ff_make_format_list(pix_fmts)); |
| 88 | } else { |
| 89 | av_assert0(0); |
| 90 | } |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | static int config_props(AVFilterLink *inlink) |
| 95 | { |
| 96 | int p; |
| 97 | AVFilterContext *ctx = inlink->dst; |
| 98 | EdgeDetectContext *edgedetect = ctx->priv; |
| 99 | |
| 100 | edgedetect->nb_planes = inlink->format == AV_PIX_FMT_GRAY8 ? 1 : 3; |
| 101 | for (p = 0; p < edgedetect->nb_planes; p++) { |
| 102 | struct plane_info *plane = &edgedetect->planes[p]; |
| 103 | |
| 104 | plane->tmpbuf = av_malloc(inlink->w * inlink->h); |
| 105 | plane->gradients = av_calloc(inlink->w * inlink->h, sizeof(*plane->gradients)); |
| 106 | plane->directions = av_malloc(inlink->w * inlink->h); |
| 107 | if (!plane->tmpbuf || !plane->gradients || !plane->directions) |
| 108 | return AVERROR(ENOMEM); |
| 109 | } |
| 110 | return 0; |
| 111 | } |
| 112 | |
| 113 | static void gaussian_blur(AVFilterContext *ctx, int w, int h, |
| 114 | uint8_t *dst, int dst_linesize, |
| 115 | const uint8_t *src, int src_linesize) |
| 116 | { |
| 117 | int i, j; |
| 118 | |
| 119 | memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
| 120 | memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
| 121 | for (j = 2; j < h - 2; j++) { |
| 122 | dst[0] = src[0]; |
| 123 | dst[1] = src[1]; |
| 124 | for (i = 2; i < w - 2; i++) { |
| 125 | /* Gaussian mask of size 5x5 with sigma = 1.4 */ |
| 126 | dst[i] = ((src[-2*src_linesize + i-2] + src[2*src_linesize + i-2]) * 2 |
| 127 | + (src[-2*src_linesize + i-1] + src[2*src_linesize + i-1]) * 4 |
| 128 | + (src[-2*src_linesize + i ] + src[2*src_linesize + i ]) * 5 |
| 129 | + (src[-2*src_linesize + i+1] + src[2*src_linesize + i+1]) * 4 |
| 130 | + (src[-2*src_linesize + i+2] + src[2*src_linesize + i+2]) * 2 |
| 131 | |
| 132 | + (src[ -src_linesize + i-2] + src[ src_linesize + i-2]) * 4 |
| 133 | + (src[ -src_linesize + i-1] + src[ src_linesize + i-1]) * 9 |
| 134 | + (src[ -src_linesize + i ] + src[ src_linesize + i ]) * 12 |
| 135 | + (src[ -src_linesize + i+1] + src[ src_linesize + i+1]) * 9 |
| 136 | + (src[ -src_linesize + i+2] + src[ src_linesize + i+2]) * 4 |
| 137 | |
| 138 | + src[i-2] * 5 |
| 139 | + src[i-1] * 12 |
| 140 | + src[i ] * 15 |
| 141 | + src[i+1] * 12 |
| 142 | + src[i+2] * 5) / 159; |
| 143 | } |
| 144 | dst[i ] = src[i ]; |
| 145 | dst[i + 1] = src[i + 1]; |
| 146 | |
| 147 | dst += dst_linesize; |
| 148 | src += src_linesize; |
| 149 | } |
| 150 | memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
| 151 | memcpy(dst, src, w); |
| 152 | } |
| 153 | |
| 154 | enum { |
| 155 | DIRECTION_45UP, |
| 156 | DIRECTION_45DOWN, |
| 157 | DIRECTION_HORIZONTAL, |
| 158 | DIRECTION_VERTICAL, |
| 159 | }; |
| 160 | |
| 161 | static int get_rounded_direction(int gx, int gy) |
| 162 | { |
| 163 | /* reference angles: |
| 164 | * tan( pi/8) = sqrt(2)-1 |
| 165 | * tan(3pi/8) = sqrt(2)+1 |
| 166 | * Gy/Gx is the tangent of the angle (theta), so Gy/Gx is compared against |
| 167 | * <ref-angle>, or more simply Gy against <ref-angle>*Gx |
| 168 | * |
| 169 | * Gx and Gy bounds = [-1020;1020], using 16-bit arithmetic: |
| 170 | * round((sqrt(2)-1) * (1<<16)) = 27146 |
| 171 | * round((sqrt(2)+1) * (1<<16)) = 158218 |
| 172 | */ |
| 173 | if (gx) { |
| 174 | int tanpi8gx, tan3pi8gx; |
| 175 | |
| 176 | if (gx < 0) |
| 177 | gx = -gx, gy = -gy; |
| 178 | gy <<= 16; |
| 179 | tanpi8gx = 27146 * gx; |
| 180 | tan3pi8gx = 158218 * gx; |
| 181 | if (gy > -tan3pi8gx && gy < -tanpi8gx) return DIRECTION_45UP; |
| 182 | if (gy > -tanpi8gx && gy < tanpi8gx) return DIRECTION_HORIZONTAL; |
| 183 | if (gy > tanpi8gx && gy < tan3pi8gx) return DIRECTION_45DOWN; |
| 184 | } |
| 185 | return DIRECTION_VERTICAL; |
| 186 | } |
| 187 | |
| 188 | static void sobel(int w, int h, |
| 189 | uint16_t *dst, int dst_linesize, |
| 190 | int8_t *dir, int dir_linesize, |
| 191 | const uint8_t *src, int src_linesize) |
| 192 | { |
| 193 | int i, j; |
| 194 | |
| 195 | for (j = 1; j < h - 1; j++) { |
| 196 | dst += dst_linesize; |
| 197 | dir += dir_linesize; |
| 198 | src += src_linesize; |
| 199 | for (i = 1; i < w - 1; i++) { |
| 200 | const int gx = |
| 201 | -1*src[-src_linesize + i-1] + 1*src[-src_linesize + i+1] |
| 202 | -2*src[ i-1] + 2*src[ i+1] |
| 203 | -1*src[ src_linesize + i-1] + 1*src[ src_linesize + i+1]; |
| 204 | const int gy = |
| 205 | -1*src[-src_linesize + i-1] + 1*src[ src_linesize + i-1] |
| 206 | -2*src[-src_linesize + i ] + 2*src[ src_linesize + i ] |
| 207 | -1*src[-src_linesize + i+1] + 1*src[ src_linesize + i+1]; |
| 208 | |
| 209 | dst[i] = FFABS(gx) + FFABS(gy); |
| 210 | dir[i] = get_rounded_direction(gx, gy); |
| 211 | } |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | static void non_maximum_suppression(int w, int h, |
| 216 | uint8_t *dst, int dst_linesize, |
| 217 | const int8_t *dir, int dir_linesize, |
| 218 | const uint16_t *src, int src_linesize) |
| 219 | { |
| 220 | int i, j; |
| 221 | |
| 222 | #define COPY_MAXIMA(ay, ax, by, bx) do { \ |
| 223 | if (src[i] > src[(ay)*src_linesize + i+(ax)] && \ |
| 224 | src[i] > src[(by)*src_linesize + i+(bx)]) \ |
| 225 | dst[i] = av_clip_uint8(src[i]); \ |
| 226 | } while (0) |
| 227 | |
| 228 | for (j = 1; j < h - 1; j++) { |
| 229 | dst += dst_linesize; |
| 230 | dir += dir_linesize; |
| 231 | src += src_linesize; |
| 232 | for (i = 1; i < w - 1; i++) { |
| 233 | switch (dir[i]) { |
| 234 | case DIRECTION_45UP: COPY_MAXIMA( 1, -1, -1, 1); break; |
| 235 | case DIRECTION_45DOWN: COPY_MAXIMA(-1, -1, 1, 1); break; |
| 236 | case DIRECTION_HORIZONTAL: COPY_MAXIMA( 0, -1, 0, 1); break; |
| 237 | case DIRECTION_VERTICAL: COPY_MAXIMA(-1, 0, 1, 0); break; |
| 238 | } |
| 239 | } |
| 240 | } |
| 241 | } |
| 242 | |
| 243 | static void double_threshold(int low, int high, int w, int h, |
| 244 | uint8_t *dst, int dst_linesize, |
| 245 | const uint8_t *src, int src_linesize) |
| 246 | { |
| 247 | int i, j; |
| 248 | |
| 249 | for (j = 0; j < h; j++) { |
| 250 | for (i = 0; i < w; i++) { |
| 251 | if (src[i] > high) { |
| 252 | dst[i] = src[i]; |
| 253 | continue; |
| 254 | } |
| 255 | |
| 256 | if ((!i || i == w - 1 || !j || j == h - 1) && |
| 257 | src[i] > low && |
| 258 | (src[-src_linesize + i-1] > high || |
| 259 | src[-src_linesize + i ] > high || |
| 260 | src[-src_linesize + i+1] > high || |
| 261 | src[ i-1] > high || |
| 262 | src[ i+1] > high || |
| 263 | src[ src_linesize + i-1] > high || |
| 264 | src[ src_linesize + i ] > high || |
| 265 | src[ src_linesize + i+1] > high)) |
| 266 | dst[i] = src[i]; |
| 267 | else |
| 268 | dst[i] = 0; |
| 269 | } |
| 270 | dst += dst_linesize; |
| 271 | src += src_linesize; |
| 272 | } |
| 273 | } |
| 274 | |
| 275 | static void color_mix(int w, int h, |
| 276 | uint8_t *dst, int dst_linesize, |
| 277 | const uint8_t *src, int src_linesize) |
| 278 | { |
| 279 | int i, j; |
| 280 | |
| 281 | for (j = 0; j < h; j++) { |
| 282 | for (i = 0; i < w; i++) |
| 283 | dst[i] = (dst[i] + src[i]) >> 1; |
| 284 | dst += dst_linesize; |
| 285 | src += src_linesize; |
| 286 | } |
| 287 | } |
| 288 | |
| 289 | static int filter_frame(AVFilterLink *inlink, AVFrame *in) |
| 290 | { |
| 291 | AVFilterContext *ctx = inlink->dst; |
| 292 | EdgeDetectContext *edgedetect = ctx->priv; |
| 293 | AVFilterLink *outlink = ctx->outputs[0]; |
| 294 | int p, direct = 0; |
| 295 | AVFrame *out; |
| 296 | |
| 297 | if (edgedetect->mode != MODE_COLORMIX && av_frame_is_writable(in)) { |
| 298 | direct = 1; |
| 299 | out = in; |
| 300 | } else { |
| 301 | out = ff_get_video_buffer(outlink, outlink->w, outlink->h); |
| 302 | if (!out) { |
| 303 | av_frame_free(&in); |
| 304 | return AVERROR(ENOMEM); |
| 305 | } |
| 306 | av_frame_copy_props(out, in); |
| 307 | } |
| 308 | |
| 309 | for (p = 0; p < edgedetect->nb_planes; p++) { |
| 310 | struct plane_info *plane = &edgedetect->planes[p]; |
| 311 | uint8_t *tmpbuf = plane->tmpbuf; |
| 312 | uint16_t *gradients = plane->gradients; |
| 313 | int8_t *directions = plane->directions; |
| 314 | |
| 315 | /* gaussian filter to reduce noise */ |
| 316 | gaussian_blur(ctx, inlink->w, inlink->h, |
| 317 | tmpbuf, inlink->w, |
| 318 | in->data[p], in->linesize[p]); |
| 319 | |
| 320 | /* compute the 16-bits gradients and directions for the next step */ |
| 321 | sobel(inlink->w, inlink->h, |
| 322 | gradients, inlink->w, |
| 323 | directions,inlink->w, |
| 324 | tmpbuf, inlink->w); |
| 325 | |
| 326 | /* non_maximum_suppression() will actually keep & clip what's necessary and |
| 327 | * ignore the rest, so we need a clean output buffer */ |
| 328 | memset(tmpbuf, 0, inlink->w * inlink->h); |
| 329 | non_maximum_suppression(inlink->w, inlink->h, |
| 330 | tmpbuf, inlink->w, |
| 331 | directions,inlink->w, |
| 332 | gradients, inlink->w); |
| 333 | |
| 334 | /* keep high values, or low values surrounded by high values */ |
| 335 | double_threshold(edgedetect->low_u8, edgedetect->high_u8, |
| 336 | inlink->w, inlink->h, |
| 337 | out->data[p], out->linesize[p], |
| 338 | tmpbuf, inlink->w); |
| 339 | |
| 340 | if (edgedetect->mode == MODE_COLORMIX) { |
| 341 | color_mix(inlink->w, inlink->h, |
| 342 | out->data[p], out->linesize[p], |
| 343 | in->data[p], in->linesize[p]); |
| 344 | } |
| 345 | } |
| 346 | |
| 347 | if (!direct) |
| 348 | av_frame_free(&in); |
| 349 | return ff_filter_frame(outlink, out); |
| 350 | } |
| 351 | |
| 352 | static av_cold void uninit(AVFilterContext *ctx) |
| 353 | { |
| 354 | int p; |
| 355 | EdgeDetectContext *edgedetect = ctx->priv; |
| 356 | |
| 357 | for (p = 0; p < edgedetect->nb_planes; p++) { |
| 358 | struct plane_info *plane = &edgedetect->planes[p]; |
| 359 | av_freep(&plane->tmpbuf); |
| 360 | av_freep(&plane->gradients); |
| 361 | av_freep(&plane->directions); |
| 362 | } |
| 363 | } |
| 364 | |
| 365 | static const AVFilterPad edgedetect_inputs[] = { |
| 366 | { |
| 367 | .name = "default", |
| 368 | .type = AVMEDIA_TYPE_VIDEO, |
| 369 | .config_props = config_props, |
| 370 | .filter_frame = filter_frame, |
| 371 | }, |
| 372 | { NULL } |
| 373 | }; |
| 374 | |
| 375 | static const AVFilterPad edgedetect_outputs[] = { |
| 376 | { |
| 377 | .name = "default", |
| 378 | .type = AVMEDIA_TYPE_VIDEO, |
| 379 | }, |
| 380 | { NULL } |
| 381 | }; |
| 382 | |
| 383 | AVFilter ff_vf_edgedetect = { |
| 384 | .name = "edgedetect", |
| 385 | .description = NULL_IF_CONFIG_SMALL("Detect and draw edge."), |
| 386 | .priv_size = sizeof(EdgeDetectContext), |
| 387 | .init = init, |
| 388 | .uninit = uninit, |
| 389 | .query_formats = query_formats, |
| 390 | .inputs = edgedetect_inputs, |
| 391 | .outputs = edgedetect_outputs, |
| 392 | .priv_class = &edgedetect_class, |
| 393 | .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, |
| 394 | }; |