120 строки
2.8 KiB
C
120 строки
2.8 KiB
C
// clang-format off
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#include <stdlib.h>
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#include "fast.h"
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#define Compare(X, Y) ((X)>=(Y))
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xy* nonmax_suppression(const xy* corners, const int* scores, int num_corners, int* ret_num_nonmax)
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{
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int num_nonmax=0;
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int last_row;
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int* row_start;
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int i, j;
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xy* ret_nonmax;
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const int sz = (int)num_corners;
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/*Point above points (roughly) to the pixel above the one of interest, if there
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is a feature there.*/
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int point_above = 0;
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int point_below = 0;
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if(num_corners < 1)
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{
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*ret_num_nonmax = 0;
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return 0;
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}
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ret_nonmax = (xy*)malloc(num_corners * sizeof(xy));
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/* Find where each row begins
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(the corners are output in raster scan order). A beginning of -1 signifies
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that there are no corners on that row. */
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last_row = corners[num_corners-1].y;
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row_start = (int*)malloc((last_row+1)*sizeof(int));
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for(i=0; i < last_row+1; i++)
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row_start[i] = -1;
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{
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int prev_row = -1;
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for(i=0; i< num_corners; i++)
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if(corners[i].y != prev_row)
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{
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row_start[corners[i].y] = i;
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prev_row = corners[i].y;
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}
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}
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for(i=0; i < sz; i++)
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{
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int score = scores[i];
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xy pos = corners[i];
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/*Check left */
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if(i > 0)
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if(corners[i-1].x == pos.x-1 && corners[i-1].y == pos.y && Compare(scores[i-1], score))
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continue;
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/*Check right*/
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if(i < (sz - 1))
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if(corners[i+1].x == pos.x+1 && corners[i+1].y == pos.y && Compare(scores[i+1], score))
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continue;
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/*Check above (if there is a valid row above)*/
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if(pos.y != 0 && row_start[pos.y - 1] != -1)
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{
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/*Make sure that current point_above is one
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row above.*/
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if(corners[point_above].y < pos.y - 1)
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point_above = row_start[pos.y-1];
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/*Make point_above point to the first of the pixels above the current point,
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if it exists.*/
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for(; corners[point_above].y < pos.y && corners[point_above].x < pos.x - 1; point_above++)
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{}
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for(j=point_above; corners[j].y < pos.y && corners[j].x <= pos.x + 1; j++)
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{
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int x = corners[j].x;
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if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j], score))
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goto cont;
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}
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}
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/*Check below (if there is anything below)*/
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if(pos.y != last_row && row_start[pos.y + 1] != -1 && point_below < sz) /*Nothing below*/
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{
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if(corners[point_below].y < pos.y + 1)
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point_below = row_start[pos.y+1];
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/* Make point below point to one of the pixels belowthe current point, if it
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exists.*/
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for(; point_below < sz && corners[point_below].y == pos.y+1 && corners[point_below].x < pos.x - 1; point_below++)
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{}
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for(j=point_below; j < sz && corners[j].y == pos.y+1 && corners[j].x <= pos.x + 1; j++)
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{
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int x = corners[j].x;
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if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j],score))
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goto cont;
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}
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}
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ret_nonmax[num_nonmax++] = corners[i];
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cont:
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;
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}
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free(row_start);
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*ret_num_nonmax = num_nonmax;
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return ret_nonmax;
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}
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// clang-format on
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