1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
// Copyright (c) 2007, 2008 libmv authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
#ifndef LIBMV_IMAGE_SAMPLE_H_
#define LIBMV_IMAGE_SAMPLE_H_
#include "libmv/image/image.h"
namespace libmv {
/// Nearest neighbor interpolation.
template<typename T>
inline T SampleNearest(const Array3D<T> &image,
float y, float x, int v = 0) {
const int i = int(round(y));
const int j = int(round(x));
return image(i, j, v);
}
inline void LinearInitAxis(float x, int size,
int *x1, int *x2,
float *dx) {
const int ix = static_cast<int>(x);
if (ix < 0) {
*x1 = 0;
*x2 = 0;
*dx = 1.0;
} else if (ix > size - 2) {
*x1 = size - 1;
*x2 = size - 1;
*dx = 1.0;
} else {
*x1 = ix;
*x2 = ix + 1;
*dx = *x2 - x;
}
}
/// Linear interpolation.
template<typename T>
inline T SampleLinear(const Array3D<T> &image, float y, float x, int v = 0) {
int x1, y1, x2, y2;
float dx, dy;
LinearInitAxis(y, image.Height(), &y1, &y2, &dy);
LinearInitAxis(x, image.Width(), &x1, &x2, &dx);
const T im11 = image(y1, x1, v);
const T im12 = image(y1, x2, v);
const T im21 = image(y2, x1, v);
const T im22 = image(y2, x2, v);
return T( dy * (dx * im11 + (1.0 - dx) * im12) +
(1 - dy) * (dx * im21 + (1.0 - dx) * im22));
}
/// Linear interpolation, of all channels. The sample is assumed to have the
/// same size as the number of channels in image.
template<typename T>
inline void SampleLinear(const Array3D<T> &image, float y, float x, T *sample) {
int x1, y1, x2, y2;
float dx, dy;
LinearInitAxis(y, image.Height(), &y1, &y2, &dy);
LinearInitAxis(x, image.Width(), &x1, &x2, &dx);
for (int i = 0; i < image.Depth(); ++i) {
const T im11 = image(y1, x1, i);
const T im12 = image(y1, x2, i);
const T im21 = image(y2, x1, i);
const T im22 = image(y2, x2, i);
sample[i] = T( dy * (dx * im11 + (1.0 - dx) * im12) +
(1 - dy) * (dx * im21 + (1.0 - dx) * im22));
}
}
// Downsample all channels by 2. If the image has odd width or height, the last
// row or column is ignored.
// FIXME(MatthiasF): this implementation shouldn't be in an interface file
inline void DownsampleChannelsBy2(const Array3Df &in, Array3Df *out) {
int height = in.Height() / 2;
int width = in.Width() / 2;
int depth = in.Depth();
out->Resize(height, width, depth);
// 2x2 box filter downsampling.
for (int r = 0; r < height; ++r) {
for (int c = 0; c < width; ++c) {
for (int k = 0; k < depth; ++k) {
(*out)(r, c, k) = (in(2 * r, 2 * c, k) +
in(2 * r + 1, 2 * c, k) +
in(2 * r, 2 * c + 1, k) +
in(2 * r + 1, 2 * c + 1, k)) / 4.0f;
}
}
}
}
// Sample a region centered at x,y in image with size extending by half_width
// from x,y. Channels specifies the number of channels to sample from.
inline void SamplePattern(const FloatImage &image,
double x, double y,
int half_width,
int channels,
FloatImage *sampled) {
sampled->Resize(2 * half_width + 1, 2 * half_width + 1, channels);
for (int r = -half_width; r <= half_width; ++r) {
for (int c = -half_width; c <= half_width; ++c) {
for (int i = 0; i < channels; ++i) {
(*sampled)(r + half_width, c + half_width, i) =
SampleLinear(image, y + r, x + c, i);
}
}
}
}
} // namespace libmv
#endif // LIBMV_IMAGE_SAMPLE_H_
|
