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- // Copyright (c) 2006, 2008 Edward Rosten
- // All rights reserved.
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions
- // are met:
- //
- // *Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- //
- // *Redistributions in binary form must reproduce the above copyright
- // notice, this list of conditions and the following disclaimer in the
- // documentation and/or other materials provided with the distribution.
- //
- // *Neither the name of the University of Cambridge nor the names of
- // its contributors may be used to endorse or promote products derived
- // from this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
- // OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- // clang-format off
- #include <stdlib.h>
- #include "fast.h"
- #define Compare(X, Y) ((X)>=(Y))
- xy* aom_nonmax_suppression(const xy* corners, const int* scores, int num_corners, int* ret_num_nonmax)
- {
- int num_nonmax=0;
- int last_row;
- int* row_start;
- int i, j;
- xy* ret_nonmax;
- const int sz = (int)num_corners;
- /*Point above points (roughly) to the pixel above the one of interest, if there
- is a feature there.*/
- int point_above = 0;
- int point_below = 0;
- if(num_corners < 1)
- {
- *ret_num_nonmax = 0;
- return 0;
- }
- ret_nonmax = (xy*)malloc(num_corners * sizeof(xy));
- /* Find where each row begins
- (the corners are output in raster scan order). A beginning of -1 signifies
- that there are no corners on that row. */
- last_row = corners[num_corners-1].y;
- row_start = (int*)malloc((last_row+1)*sizeof(int));
- for(i=0; i < last_row+1; i++)
- row_start[i] = -1;
- {
- int prev_row = -1;
- for(i=0; i< num_corners; i++)
- if(corners[i].y != prev_row)
- {
- row_start[corners[i].y] = i;
- prev_row = corners[i].y;
- }
- }
- for(i=0; i < sz; i++)
- {
- int score = scores[i];
- xy pos = corners[i];
- /*Check left */
- if(i > 0)
- if(corners[i-1].x == pos.x-1 && corners[i-1].y == pos.y && Compare(scores[i-1], score))
- continue;
- /*Check right*/
- if(i < (sz - 1))
- if(corners[i+1].x == pos.x+1 && corners[i+1].y == pos.y && Compare(scores[i+1], score))
- continue;
- /*Check above (if there is a valid row above)*/
- if(pos.y > 0)
- if (row_start[pos.y - 1] != -1)
- {
- /*Make sure that current point_above is one
- row above.*/
- if(corners[point_above].y < pos.y - 1)
- point_above = row_start[pos.y-1];
- /*Make point_above point to the first of the pixels above the current point,
- if it exists.*/
- for(; corners[point_above].y < pos.y && corners[point_above].x < pos.x - 1; point_above++)
- {}
- for(j=point_above; corners[j].y < pos.y && corners[j].x <= pos.x + 1; j++)
- {
- int x = corners[j].x;
- if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j], score))
- goto cont;
- }
- }
- /*Check below (if there is anything below)*/
- if(pos.y >= 0)
- if (pos.y != last_row && row_start[pos.y + 1] != -1 && point_below < sz) /*Nothing below*/
- {
- if(corners[point_below].y < pos.y + 1)
- point_below = row_start[pos.y+1];
- /* Make point below point to one of the pixels belowthe current point, if it
- exists.*/
- for(; point_below < sz && corners[point_below].y == pos.y+1 && corners[point_below].x < pos.x - 1; point_below++)
- {}
- for(j=point_below; j < sz && corners[j].y == pos.y+1 && corners[j].x <= pos.x + 1; j++)
- {
- int x = corners[j].x;
- if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j],score))
- goto cont;
- }
- }
- ret_nonmax[num_nonmax++] = corners[i];
- cont:
- ;
- }
- free(row_start);
- *ret_num_nonmax = num_nonmax;
- return ret_nonmax;
- }
- // clang-format on
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