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vigra/rfftw.hxx |

    00001 /************************************************************************/
    00002 /*                                                                      */
    00003 /*               Copyright 1998-2002 by Ullrich Koethe                  */
    00004 /*                                                                      */
    00005 /*    This file is part of the VIGRA computer vision library.           */
    00006 /*    The VIGRA Website is                                              */
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    00009 /*        ullrich.koethe@iwr.uni-heidelberg.de    or                    */
    00010 /*        vigra@informatik.uni-hamburg.de                               */
    00011 /*                                                                      */
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    00019 /*    conditions:                                                       */
    00020 /*                                                                      */
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    00023 /*    Software.                                                         */
    00024 /*                                                                      */
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    00027 /*    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND          */
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    00033 /*                                                                      */
    00034 /************************************************************************/
    00035
    00036 #ifndef VIGRA_RFFTW_HXX
    00037 #define VIGRA_RFFTW_HXX
    00038
    00039 #include "array_vector.hxx"
    00040 #include "fftw.hxx"
    00041 #include <rfftw.h>
    00042
    00043 namespace vigra {
    00044
    00045 namespace detail {
    00046
    00047 struct FFTWSinCosConfig
    00048 {
    00049     ArrayVector<fftw_real> twiddles;
    00050     ArrayVector<fftw_real> fftwInput;
    00051     ArrayVector<fftw_complex> fftwTmpResult;
    00052     fftw_real norm;
    00053     rfftwnd_plan fftwPlan;
    00054 };
    00055
    00056 template <class SrcIterator, class SrcAccessor,
    00057           class DestIterator, class DestAccessor,
    00058           class Config>
    00059 void
    00060 cosineTransformLineImpl(SrcIterator s, SrcIterator send, SrcAccessor src,
    00061                         DestIterator d, DestAccessor dest,
    00062                         Config & config)
    00063 {
    00064     int size = send - s;
    00065     int ns2 = size / 2;
    00066     int nm1 = size - 1;
    00067     int modn = size % 2;
    00068
    00069     if(size <= 0)
    00070         return;
    00071
    00072     fftw_real const * twiddles = config.twiddles.begin();
    00073     fftw_real * fftwInput = config.fftwInput.begin();
    00074     fftw_complex * fftwTmpResult = config.fftwTmpResult.begin();
    00075     fftw_real norm = config.norm;
    00076     rfftwnd_plan fftwPlan = config.fftwPlan;
    00077
    00078     switch(size)
    00079     {
    00080       case 1:
    00081       {
    00082         dest.set(src(s) / norm, d);
    00083         break;
    00084       }
    00085       case 2:
    00086       {
    00087         dest.set((src(s) + src(s, 1)) / norm, d);
    00088         dest.set((src(s) - src(s, 1)) / norm, d, 1);
    00089         break;
    00090       }
    00091       case 3:
    00092       {
    00093         fftw_real x1p3 = src(s) + src(s, 2);
    00094         fftw_real tx2 =  2.0 * src(s, 1);
    00095
    00096         dest.set((x1p3 + tx2) / norm, d, 0);
    00097         dest.set((src(s) - src(s, 2)) / norm, d, 1);
    00098         dest.set((x1p3 - tx2) / norm, d, 2);
    00099         break;
    00100       }
    00101       default:
    00102       {
    00103         fftw_real c1 = src(s) - src(s, nm1);
    00104         fftwInput[0] = src(s) + src(s, nm1);
    00105         for(int k=1; k<ns2; ++k)
    00106         {
    00107             int kc = nm1 - k;
    00108             fftw_real t1 = src(s, k) + src(s, kc);
    00109             fftw_real t2 = src(s, k) - src(s, kc);
    00110             c1 = c1 + twiddles[kc] * t2;
    00111             t2 = twiddles[k] * t2;
    00112             fftwInput[k] = t1 - t2;
    00113             fftwInput[kc] = t1 + t2;
    00114         }
    00115
    00116         if (modn != 0)
    00117         {
    00118             fftwInput[ns2] = 2.0*src(s, ns2);
    00119         }
    00120         rfftwnd_one_real_to_complex(fftwPlan, fftwInput, fftwTmpResult);
    00121         dest.set(fftwTmpResult[0].re / norm, d, 0);
    00122         for(int k=1; k<(size+1)/2; ++k)
    00123         {
    00124             dest.set(fftwTmpResult[k].re, d, 2*k-1);
    00125             dest.set(fftwTmpResult[k].im, d, 2*k);
    00126         }
    00127         fftw_real xim2 = dest(d, 1);
    00128         dest.set(c1 / norm, d, 1);
    00129         for(int k=3; k<size; k+=2)
    00130         {
    00131             fftw_real xi = dest(d, k);
    00132             dest.set(dest(d, k-2) - dest(d, k-1) / norm, d, k);
    00133             dest.set(xim2 / norm, d, k-1);
    00134             xim2 = xi;
    00135         }
    00136         if (modn != 0)
    00137         {
    00138             dest.set(xim2 / norm, d, size-1);
    00139         }
    00140       }
    00141     }
    00142 }
    00143
    00144 } // namespace detail
    00145
    00146 template <class SrcTraverser, class SrcAccessor,
    00147           class DestTraverser, class DestAccessor>
    00148 void cosineTransformX(SrcTraverser sul, SrcTraverser slr, SrcAccessor src,
    00149                       DestTraverser dul, DestAccessor dest, fftw_real norm)
    00150 {
    00151     int w = slr.x - sul.x;
    00152     int h = slr.y - sul.y;
    00153
    00154     detail::FFTWSinCosConfig config;
    00155
    00156     // horizontal transformation
    00157     int ns2 = w / 2;
    00158     int nm1 = w - 1;
    00159     int modn = w % 2;
    00160
    00161     config.twiddles.resize(w+1);
    00162     config.fftwInput.resize(w+1);
    00163     config.fftwTmpResult.resize(w+1);
    00164     config.norm = norm;
    00165     config.fftwPlan = rfftw2d_create_plan(1, nm1, FFTW_REAL_TO_COMPLEX, FFTW_ESTIMATE );
    00166
    00167     fftw_real dt = M_PI / nm1;
    00168     for(int k=1; k<ns2; ++k)
    00169     {
    00170         fftw_real f = dt * k;
    00171         config.twiddles[k] = 2.0*VIGRA_CSTD::sin(f);
    00172         config.twiddles[nm1-k] = 2.0*VIGRA_CSTD::cos(f);
    00173     }
    00174
    00175     for(; sul.y != slr.y; ++sul.y, ++dul.y)
    00176     {
    00177         typename SrcTraverser::row_iterator s = sul.rowIterator();
    00178         typename SrcTraverser::row_iterator send = s + w;
    00179         typename DestTraverser::row_iterator d = dul.rowIterator();
    00180         cosineTransformLineImpl(s, send, src, d, dest, config);
    00181     }
    00182
    00183     rfftwnd_destroy_plan(config.fftwPlan);
    00184 }
    00185
    00186 template <class SrcTraverser, class SrcAccessor,
    00187           class DestTraverser, class DestAccessor>
    00188 void cosineTransformY(SrcTraverser sul, SrcTraverser slr, SrcAccessor src,
    00189                       DestTraverser dul, DestAccessor dest, fftw_real norm)
    00190 {
    00191     int w = slr.x - sul.x;
    00192     int h = slr.y - sul.y;
    00193
    00194     detail::FFTWSinCosConfig config;
    00195
    00196     // horizontal transformation
    00197     int ns2 = h / 2;
    00198     int nm1 = h - 1;
    00199     int modn = h % 2;
    00200
    00201     config.twiddles.resize(h + 1);
    00202     config.fftwInput.resize(h + 1);
    00203     config.fftwTmpResult.resize(h + 1);
    00204     config.norm = norm;
    00205     config.fftwPlan = rfftw2d_create_plan(1, nm1, FFTW_REAL_TO_COMPLEX, FFTW_ESTIMATE );
    00206
    00207     fftw_real dt = M_PI / nm1;
    00208     for(int k=1; k<ns2; ++k)
    00209     {
    00210         fftw_real f = dt * k;
    00211         config.twiddles[k] = 2.0*VIGRA_CSTD::sin(f);
    00212         config.twiddles[nm1-k] = 2.0*VIGRA_CSTD::cos(f);
    00213     }
    00214
    00215     for(; sul.x != slr.x; ++sul.x, ++dul.x)
    00216     {
    00217         typename SrcTraverser::column_iterator s = sul.columnIterator();
    00218         typename SrcTraverser::column_iterator send = s + h;
    00219         typename DestTraverser::column_iterator d = dul.columnIterator();
    00220         cosineTransformLineImpl(s, send, src, d, dest, config);
    00221     }
    00222
    00223     rfftwnd_destroy_plan(config.fftwPlan);
    00224 }
    00225
    00226 template <class SrcTraverser, class SrcAccessor,
    00227           class DestTraverser, class DestAccessor>
    00228 inline void
    00229 realFourierTransformXEvenYEven(SrcTraverser sul, SrcTraverser slr, SrcAccessor src,
    00230                       DestTraverser dul, DestAccessor dest, fftw_real norm)
    00231 {
    00232     BasicImage<fftw_real> tmp(slr - sul);
    00233     cosineTransformX(sul, slr, src, tmp.upperLeft(), tmp.accessor(), 1.0);
    00234     cosineTransformY(tmp.upperLeft(), tmp.lowerRight(), tmp.accessor(), dul, dest, norm);
    00235 }
    00236
    00237 template <class SrcTraverser, class SrcAccessor,
    00238           class DestTraverser, class DestAccessor>
    00239 inline void
    00240 realFourierTransformXEvenYEven(triple<SrcTraverser, SrcTraverser, SrcAccessor> src,
    00241                       pair<DestTraverser, DestAccessor> dest, fftw_real norm)
    00242 {
    00243     realFourierTransformXEvenYEven(src.first, src.second, src.third, dest.first, dest.second, norm);
    00244 }
    00245
    00246 } // namespace vigra
    00247
    00248 #endif // VIGRA_RFFTW_HXX

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.7.1 (3 Dec 2010)