mirror of https://github.com/FFmpeg/FFmpeg.git
Thilo Borgmann
3 years ago
parent
f2724d2b69
commit
22df52c444
4 changed files with 296 additions and 177 deletions
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/*
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "edge_common.h" |
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// Internal helper for ff_sobel()
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static int get_rounded_direction(int gx, int gy) |
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{ |
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/* reference angles:
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* tan( pi/8) = sqrt(2)-1 |
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* tan(3pi/8) = sqrt(2)+1 |
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* Gy/Gx is the tangent of the angle (theta), so Gy/Gx is compared against |
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* <ref-angle>, or more simply Gy against <ref-angle>*Gx |
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* |
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* Gx and Gy bounds = [-1020;1020], using 16-bit arithmetic: |
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* round((sqrt(2)-1) * (1<<16)) = 27146 |
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* round((sqrt(2)+1) * (1<<16)) = 158218 |
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*/ |
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if (gx) { |
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int tanpi8gx, tan3pi8gx; |
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if (gx < 0) |
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gx = -gx, gy = -gy; |
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gy *= (1 << 16); |
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tanpi8gx = 27146 * gx; |
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tan3pi8gx = 158218 * gx; |
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if (gy > -tan3pi8gx && gy < -tanpi8gx) return DIRECTION_45UP; |
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if (gy > -tanpi8gx && gy < tanpi8gx) return DIRECTION_HORIZONTAL; |
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if (gy > tanpi8gx && gy < tan3pi8gx) return DIRECTION_45DOWN; |
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} |
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return DIRECTION_VERTICAL; |
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} |
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// Simple sobel operator to get rounded gradients
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void ff_sobel(int w, int h, |
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uint16_t *dst, int dst_linesize, |
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int8_t *dir, int dir_linesize, |
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const uint8_t *src, int src_linesize) |
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{ |
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int i, j; |
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for (j = 1; j < h - 1; j++) { |
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dst += dst_linesize; |
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dir += dir_linesize; |
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src += src_linesize; |
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for (i = 1; i < w - 1; i++) { |
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const int gx = |
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-1*src[-src_linesize + i-1] + 1*src[-src_linesize + i+1] |
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-2*src[ i-1] + 2*src[ i+1] |
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-1*src[ src_linesize + i-1] + 1*src[ src_linesize + i+1]; |
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const int gy = |
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-1*src[-src_linesize + i-1] + 1*src[ src_linesize + i-1] |
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-2*src[-src_linesize + i ] + 2*src[ src_linesize + i ] |
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-1*src[-src_linesize + i+1] + 1*src[ src_linesize + i+1]; |
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dst[i] = FFABS(gx) + FFABS(gy); |
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dir[i] = get_rounded_direction(gx, gy); |
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} |
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} |
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} |
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// Filters rounded gradients to drop all non-maxima
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// Expects gradients generated by ff_sobel()
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// Expects zero's destination buffer
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void ff_non_maximum_suppression(int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const int8_t *dir, int dir_linesize, |
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const uint16_t *src, int src_linesize) |
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{ |
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int i, j; |
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#define COPY_MAXIMA(ay, ax, by, bx) do { \ |
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if (src[i] > src[(ay)*src_linesize + i+(ax)] && \
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src[i] > src[(by)*src_linesize + i+(bx)]) \
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dst[i] = av_clip_uint8(src[i]); \
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} while (0) |
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for (j = 1; j < h - 1; j++) { |
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dst += dst_linesize; |
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dir += dir_linesize; |
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src += src_linesize; |
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for (i = 1; i < w - 1; i++) { |
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switch (dir[i]) { |
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case DIRECTION_45UP: COPY_MAXIMA( 1, -1, -1, 1); break; |
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case DIRECTION_45DOWN: COPY_MAXIMA(-1, -1, 1, 1); break; |
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case DIRECTION_HORIZONTAL: COPY_MAXIMA( 0, -1, 0, 1); break; |
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case DIRECTION_VERTICAL: COPY_MAXIMA(-1, 0, 1, 0); break; |
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} |
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} |
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} |
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} |
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// Filter to keep all pixels > high, and keep all pixels > low where all surrounding pixels > high
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void ff_double_threshold(int low, int high, int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const uint8_t *src, int src_linesize) |
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{ |
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int i, j; |
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for (j = 0; j < h; j++) { |
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for (i = 0; i < w; i++) { |
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if (src[i] > high) { |
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dst[i] = src[i]; |
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continue; |
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} |
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if (!(!i || i == w - 1 || !j || j == h - 1) && |
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src[i] > low && |
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(src[-src_linesize + i-1] > high || |
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src[-src_linesize + i ] > high || |
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src[-src_linesize + i+1] > high || |
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src[ i-1] > high || |
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src[ i+1] > high || |
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src[ src_linesize + i-1] > high || |
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src[ src_linesize + i ] > high || |
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src[ src_linesize + i+1] > high)) |
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dst[i] = src[i]; |
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else |
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dst[i] = 0; |
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} |
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dst += dst_linesize; |
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src += src_linesize; |
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} |
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} |
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// Applies gaussian blur, using 5x5 kernels, sigma = 1.4
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void ff_gaussian_blur(int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const uint8_t *src, int src_linesize) |
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{ |
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int i, j; |
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memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
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memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
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for (j = 2; j < h - 2; j++) { |
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dst[0] = src[0]; |
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dst[1] = src[1]; |
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for (i = 2; i < w - 2; i++) { |
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/* Gaussian mask of size 5x5 with sigma = 1.4 */ |
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dst[i] = ((src[-2*src_linesize + i-2] + src[2*src_linesize + i-2]) * 2 |
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+ (src[-2*src_linesize + i-1] + src[2*src_linesize + i-1]) * 4 |
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+ (src[-2*src_linesize + i ] + src[2*src_linesize + i ]) * 5 |
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+ (src[-2*src_linesize + i+1] + src[2*src_linesize + i+1]) * 4 |
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+ (src[-2*src_linesize + i+2] + src[2*src_linesize + i+2]) * 2 |
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+ (src[ -src_linesize + i-2] + src[ src_linesize + i-2]) * 4 |
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+ (src[ -src_linesize + i-1] + src[ src_linesize + i-1]) * 9 |
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+ (src[ -src_linesize + i ] + src[ src_linesize + i ]) * 12 |
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+ (src[ -src_linesize + i+1] + src[ src_linesize + i+1]) * 9 |
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+ (src[ -src_linesize + i+2] + src[ src_linesize + i+2]) * 4 |
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+ src[i-2] * 5 |
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+ src[i-1] * 12 |
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+ src[i ] * 15 |
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+ src[i+1] * 12 |
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+ src[i+2] * 5) / 159; |
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} |
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dst[i ] = src[i ]; |
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dst[i + 1] = src[i + 1]; |
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dst += dst_linesize; |
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src += src_linesize; |
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} |
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memcpy(dst, src, w); dst += dst_linesize; src += src_linesize; |
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memcpy(dst, src, w); |
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} |
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@ -0,0 +1,107 @@ |
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/*
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/**
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* @file |
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* common functions for edge detection |
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*/ |
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#ifndef AVFILTER_EDGE_COMMON_H |
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#define AVFILTER_EDGE_COMMON_H |
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#include "avfilter.h" |
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/**
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* @brief Rounded directions used in av_image_sobel() |
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*/ |
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enum AVRoundedDirection { |
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DIRECTION_45UP, |
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DIRECTION_45DOWN, |
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DIRECTION_HORIZONTAL, |
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DIRECTION_VERTICAL, |
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}; |
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|
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/**
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* Simple sobel operator to get rounded gradients |
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* |
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* @param w the width of the image in pixels |
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* @param h the height of the image in pixels |
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* @param dst data pointers to magnitude image |
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* @param dst_linesize linesizes for the magnitude image |
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* @param dir data pointers to direction image |
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* @param dir_linesize linesizes for the direction image |
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* @param src data pointers to source image |
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* @param src_linesize linesizes for the source image |
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*/ |
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void ff_sobel(int w, int h, |
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uint16_t *dst, int dst_linesize, |
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int8_t *dir, int dir_linesize, |
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const uint8_t *src, int src_linesize); |
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/**
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* Filters rounded gradients to drop all non-maxima pixels in the magnitude image |
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* Expects gradients generated by av_image_sobel() |
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* Expects zero's in the destination buffer dst |
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* |
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* @param w the width of the image in pixels |
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* @param h the height of the image in pixels |
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* @param dst data pointers to magnitude image |
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* @param dst_linesize linesizes for the magnitude image |
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* @param dir data pointers to direction image |
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* @param dir_linesize linesizes for the direction image |
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* @param src data pointers to source image |
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* @param src_linesize linesizes for the source image |
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*/ |
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void ff_non_maximum_suppression(int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const int8_t *dir, int dir_linesize, |
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const uint16_t *src, int src_linesize); |
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/**
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* Filters all pixels in src to keep all pixels > high, |
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* and keep all pixels > low where all surrounding pixels > high |
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* |
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* @param low the low threshold value |
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* @param high the hegh threshold value |
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* @param w the width of the image in pixels |
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* @param h the height of the image in pixels |
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* @param dst data pointers to destination image |
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* @param dst_linesize linesizes for the destination image |
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* @param src data pointers to source image |
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* @param src_linesize linesizes for the source image |
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*/ |
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void ff_double_threshold(int low, int high, int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const uint8_t *src, int src_linesize); |
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/**
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* Applies gaussian blur. |
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* 5x5 kernels, sigma = 1.4 |
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* |
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* @param w the width of the image in pixels |
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* @param h the height of the image in pixels |
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* @param dst data pointers to destination image |
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* @param dst_linesize linesizes for the destination image |
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* @param src data pointers to source image |
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* @param src_linesize linesizes for the source image |
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*/ |
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void ff_gaussian_blur(int w, int h, |
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uint8_t *dst, int dst_linesize, |
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const uint8_t *src, int src_linesize); |
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#endif |
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