120 lines
4.1 KiB
C
120 lines
4.1 KiB
C
/*
|
|
* 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
|
|
*/
|
|
|
|
#include "edge_common.h"
|
|
|
|
// Internal helper for ff_sobel()
|
|
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 *= (1 << 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;
|
|
}
|
|
|
|
#undef DEPTH
|
|
#define DEPTH 8
|
|
#include "edge_template.c"
|
|
|
|
#undef DEPTH
|
|
#define DEPTH 16
|
|
#include "edge_template.c"
|
|
|
|
// Filters rounded gradients to drop all non-maxima
|
|
// Expects gradients generated by ff_sobel()
|
|
// Expects zero's destination buffer
|
|
void ff_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;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Filter to keep all pixels > high, and keep all pixels > low where all surrounding pixels > high
|
|
void ff_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;
|
|
}
|
|
}
|