/src/gdal/alg/gdalresamplingkernels.h
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1 | | /****************************************************************************** |
2 | | * $Id$ |
3 | | * |
4 | | * Project: GDAL Raster Interpolation |
5 | | * Purpose: Interpolation algorithms with cache |
6 | | * Author: Frank Warmerdam, warmerdam@pobox.com |
7 | | * |
8 | | ****************************************************************************** |
9 | | * Copyright (c) 2001, Frank Warmerdam |
10 | | * Copyright (c) 2008-2012, Even Rouault <even dot rouault at spatialys.com> |
11 | | * Copyright (c) 2024, Javier Jimenez Shaw |
12 | | * |
13 | | * SPDX-License-Identifier: MIT |
14 | | ****************************************************************************/ |
15 | | |
16 | | #ifndef GDALRESAMPLINGKERNELS_H_INCLUDED |
17 | | #define GDALRESAMPLINGKERNELS_H_INCLUDED |
18 | | |
19 | | #include <cmath> |
20 | | |
21 | | /*! @cond Doxygen_Suppress */ |
22 | | |
23 | | static inline double CubicKernel(double dfX) |
24 | 0 | { |
25 | | // http://en.wikipedia.org/wiki/Bicubic_interpolation#Bicubic_convolution_algorithm |
26 | | // W(x) formula with a = -0.5 (cubic hermite spline ) |
27 | | // or |
28 | | // https://www.cs.utexas.edu/~fussell/courses/cs384g-fall2013/lectures/mitchell/Mitchell.pdf |
29 | | // k(x) (formula 8) with (B,C)=(0,0.5) the Catmull-Rom spline |
30 | 0 | double dfAbsX = fabs(dfX); |
31 | 0 | if (dfAbsX <= 1.0) |
32 | 0 | { |
33 | 0 | double dfX2 = dfX * dfX; |
34 | 0 | return dfX2 * (1.5 * dfAbsX - 2.5) + 1; |
35 | 0 | } |
36 | 0 | else if (dfAbsX <= 2.0) |
37 | 0 | { |
38 | 0 | double dfX2 = dfX * dfX; |
39 | 0 | return dfX2 * (-0.5 * dfAbsX + 2.5) - 4 * dfAbsX + 2; |
40 | 0 | } |
41 | 0 | else |
42 | 0 | return 0.0; |
43 | 0 | } Unexecuted instantiation: gdalwarpkernel.cpp:CubicKernel(double) Unexecuted instantiation: gdal_interpolateatpoint.cpp:CubicKernel(double) Unexecuted instantiation: gdal_rpc.cpp:CubicKernel(double) |
44 | | |
45 | | static inline double CubicSplineKernel(double dfVal) |
46 | 0 | { |
47 | 0 | if (dfVal > 2.0) |
48 | 0 | return 0.0; |
49 | | |
50 | 0 | const double xm1 = dfVal - 1.0; |
51 | 0 | const double xp1 = dfVal + 1.0; |
52 | 0 | const double xp2 = dfVal + 2.0; |
53 | |
|
54 | 0 | const double a = xp2 <= 0.0 ? 0.0 : xp2 * xp2 * xp2; |
55 | 0 | const double b = xp1 <= 0.0 ? 0.0 : xp1 * xp1 * xp1; |
56 | 0 | const double c = dfVal <= 0.0 ? 0.0 : dfVal * dfVal * dfVal; |
57 | 0 | const double d = xm1 <= 0.0 ? 0.0 : xm1 * xm1 * xm1; |
58 | |
|
59 | 0 | return 0.16666666666666666667 * (a - (4.0 * b) + (6.0 * c) - (4.0 * d)); |
60 | 0 | } Unexecuted instantiation: gdalwarpkernel.cpp:CubicSplineKernel(double) Unexecuted instantiation: gdal_interpolateatpoint.cpp:CubicSplineKernel(double) Unexecuted instantiation: gdal_rpc.cpp:CubicSplineKernel(double) |
61 | | |
62 | | /*! @endcond */ |
63 | | |
64 | | #endif /* ndef GDALRESAMPLINGKERNELS_H_INCLUDED */ |