1 // Copyright (c) 2006, 2008 Edward Rosten
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions
6 // are met:
7 //
8 // *Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 //
11 // *Redistributions in binary form must reproduce the above copyright
12 // notice, this list of conditions and the following disclaimer in the
13 // documentation and/or other materials provided with the distribution.
14 //
15 // *Neither the name of the University of Cambridge nor the names of
16 // its contributors may be used to endorse or promote products derived
17 // from this software without specific prior written permission.
18 //
19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
23 // OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31 // clang-format off
32 #include <stdlib.h>
33 #include "fast.h"
34
35
36 #define Compare(X, Y) ((X)>=(Y))
37
aom_nonmax_suppression(const xy * corners,const int * scores,int num_corners,int * ret_num_nonmax)38 xy* aom_nonmax_suppression(const xy* corners, const int* scores, int num_corners, int* ret_num_nonmax)
39 {
40 int num_nonmax=0;
41 int last_row;
42 int* row_start;
43 int i, j;
44 xy* ret_nonmax;
45 const int sz = (int)num_corners;
46
47 /*Point above points (roughly) to the pixel above the one of interest, if there
48 is a feature there.*/
49 int point_above = 0;
50 int point_below = 0;
51
52 *ret_num_nonmax = 0;
53 if(!(corners && scores) || num_corners < 1)
54 {
55 return 0;
56 }
57
58 ret_nonmax = (xy*)malloc(num_corners * sizeof(xy));
59 if(!ret_nonmax)
60 {
61 return 0;
62 }
63
64 /* Find where each row begins
65 (the corners are output in raster scan order). A beginning of -1 signifies
66 that there are no corners on that row. */
67 last_row = corners[num_corners-1].y;
68 row_start = (int*)malloc((last_row+1)*sizeof(int));
69 if(!row_start)
70 {
71 free(ret_nonmax);
72 return 0;
73 }
74
75 for(i=0; i < last_row+1; i++)
76 row_start[i] = -1;
77
78 {
79 int prev_row = -1;
80 for(i=0; i< num_corners; i++)
81 if(corners[i].y != prev_row)
82 {
83 row_start[corners[i].y] = i;
84 prev_row = corners[i].y;
85 }
86 }
87
88
89
90 for(i=0; i < sz; i++)
91 {
92 int score = scores[i];
93 xy pos = corners[i];
94
95 /*Check left */
96 if(i > 0)
97 if(corners[i-1].x == pos.x-1 && corners[i-1].y == pos.y && Compare(scores[i-1], score))
98 continue;
99
100 /*Check right*/
101 if(i < (sz - 1))
102 if(corners[i+1].x == pos.x+1 && corners[i+1].y == pos.y && Compare(scores[i+1], score))
103 continue;
104
105 /*Check above (if there is a valid row above)*/
106 if(pos.y > 0)
107 if (row_start[pos.y - 1] != -1)
108 {
109 /*Make sure that current point_above is one
110 row above.*/
111 if(corners[point_above].y < pos.y - 1)
112 point_above = row_start[pos.y-1];
113
114 /*Make point_above point to the first of the pixels above the current point,
115 if it exists.*/
116 for(; corners[point_above].y < pos.y && corners[point_above].x < pos.x - 1; point_above++)
117 {}
118
119
120 for(j=point_above; corners[j].y < pos.y && corners[j].x <= pos.x + 1; j++)
121 {
122 int x = corners[j].x;
123 if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j], score))
124 goto cont;
125 }
126
127 }
128
129 /*Check below (if there is anything below)*/
130 if(pos.y >= 0)
131 if (pos.y != last_row && row_start[pos.y + 1] != -1 && point_below < sz) /*Nothing below*/
132 {
133 if(corners[point_below].y < pos.y + 1)
134 point_below = row_start[pos.y+1];
135
136 /* Make point below point to one of the pixels belowthe current point, if it
137 exists.*/
138 for(; point_below < sz && corners[point_below].y == pos.y+1 && corners[point_below].x < pos.x - 1; point_below++)
139 {}
140
141 for(j=point_below; j < sz && corners[j].y == pos.y+1 && corners[j].x <= pos.x + 1; j++)
142 {
143 int x = corners[j].x;
144 if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j],score))
145 goto cont;
146 }
147 }
148
149 ret_nonmax[num_nonmax++] = corners[i];
150 cont:
151 ;
152 }
153
154 free(row_start);
155 *ret_num_nonmax = num_nonmax;
156 return ret_nonmax;
157 }
158
159 // clang-format on
160