* mln/transform/fft.hh: Here. --- milena/ChangeLog | 6 + milena/mln/transform/fft.hh | 630 ++++++++++++++++++++----------------------- 2 files changed, 305 insertions(+), 331 deletions(-) diff --git a/milena/ChangeLog b/milena/ChangeLog index 55c1dcc..faa5f7b 100644 --- a/milena/ChangeLog +++ b/milena/ChangeLog @@ -1,5 +1,11 @@ 2012-10-10 Roland Levillain <roland@lrde.epita.fr> + Stylistic changes in the Fast Fourier Transform. + + * mln/transform/fft.hh: Here. + +2012-10-10 Roland Levillain <roland@lrde.epita.fr> + Remove dead code in the Fast Fourier Transform. * mln/transform/fft.hh: Here. diff --git a/milena/mln/transform/fft.hh b/milena/mln/transform/fft.hh index dfbe1d7..9b70b4f 100644 --- a/milena/mln/transform/fft.hh +++ b/milena/mln/transform/fft.hh @@ -27,17 +27,20 @@ #ifndef MLN_TRANSFORM_FFT_HH # define MLN_TRANSFORM_FFT_HH -# include <mln/core/image/image2d.hh> -# include <mln/estim/min_max.hh> -# include <mln/opt/at.hh> +# include <complex> -# include <complex> +# include <fftw3.h> -# include <fftw3.h> +# include <mln/core/image/image2d.hh> +# include <mln/estim/min_max.hh> +# include <mln/opt/at.hh> -namespace mln { - namespace internal { +namespace mln +{ + + namespace internal + { /// Dispatch traits for fftw enum fft_dispatch { fft_cplx, fft_real }; @@ -45,316 +48,279 @@ namespace mln { template <typename T> struct fft_trait; - /*! - ** \brief fft trait. - */ + /// \brief FFT traits for `double'. template <> struct fft_trait<double> { - static const fft_dispatch which = fft_real; ///< Real dispatch. - typedef double fftw_input; ///< Type of input. + /// Type of dispatch (real numbers). + static const fft_dispatch which = fft_real; + /// Type of input (double-precision floating point numbers). + typedef double fftw_input; }; - /*! - ** \brief fft trait. - ** - ** \specialization for ntg::cplx<R, T> - */ + /// \brief FFT traits for `std::complex<T>'. template <typename T> struct fft_trait< std::complex<T> > { - static const fft_dispatch which = fft_cplx; ///< Complex dispatch. - typedef std::complex <T> fftw_input; ///< Type of input. + /// Type of dispatch (complex numbers). + static const fft_dispatch which = fft_cplx; + /// Type of input (complex numbers of the standard C++ library). + typedef std::complex<T> fftw_input; }; - /*! - ** _fft<ntg::cplx_representation, T> - ** - ** \param T Data type. - */ + /// \brief Internal structure containining packing data and + /// instructions for the (forward) and inverse (backward) + /// transforms. + /// + /// \tparam T Data type. template <class T> - class _fft + class fft { public: - /*! - ** \brief Accessor to transformed image. - ** - ** Const version. - */ + /// \brief Accessor to transformed image (const version). const image2d< std::complex<T> >& transformed_image() const { return trans_im; } - /*! - ** \brief Accessor to transformed image. - ** - ** Non const version. - */ + /// \brief Accessor to transformed image (non const version). image2d< std::complex<T> >& transformed_image() { return trans_im; } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** |T[p]|. - ** - ** \tparam R Data type of the resulting image. - ** - ** \param ordered Kind of traversal. - */ + /// \brief Accessor to the transformed image (magnitude). + /// + /// For each point \p p of the transformed image \p T, + /// an image containing <tt>|T[p]|</tt> is returned. + /// + /// \tparam R Value type of the resulting image. + /// + /// \param ordered Kind of traversal. template <class R> image2d<R> transformed_image_magn(bool ordered = true) const { - // FIXME : check that R is real + // FIXME: Ensure R is real. + const unsigned nrows = trans_im.nrows(); + const unsigned ncols = trans_im.ncols(); image2d<R> new_im(trans_im.domain()); - if (ordered) for (unsigned row = 0; row < new_im.nrows(); ++row) for (unsigned col = 0; col < new_im.ncols(); ++col) opt::at(new_im, row, col) = - std::norm(opt::at(trans_im, (row + trans_im.nrows() / 2) % trans_im.nrows(), - (col + trans_im.ncols() / 2) % trans_im.ncols())); + std::norm(opt::at(trans_im, + (row + nrows / 2) % nrows, + (col + ncols / 2) % ncols)); else { mln_piter(image2d< std::complex<T> >) it(trans_im.domain()); - for_all(it) new_im(it) = std::norm(trans_im(it)); } - return new_im; } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** |T[p]|. - ** - ** \param ordered Kind of traversal. - */ + /// \brief Accessor to the transformed image (magnitude). + /// + /// For each point \p p of the transformed image \p T, + /// an image containing <tt>|T[p]|</tt> is returned. + /// + /// \param ordered Kind of traversal. image2d<T> transformed_image_magn(bool ordered = true) const { return transformed_image_magn<T>(ordered); } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a clipped value of |T[p]|.\n - ** - ** \param R Data type of the resulting image. - ** - ** \param clip Value used for clipping. - ** \param ordered Kind of traversal. - */ - + /// \brief Accessor to the transformed image (clipped + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a clipped value of <tt>|T[p]|</tt> is returned. + /// + /// \tparam R Value type of the resulting image. + /// + /// \param clip Value used for clipping. + /// \param ordered Kind of traversal. template <class R> image2d<R> transformed_image_clipped_magn(double clip, bool ordered = true) const { - // Check that R is real + // FIXME: Ensure R is real. + // FIXME: Ensure `clip' is between 0 and 1? - image2d<R> new_im(trans_im.domain()); - // check that clip is >=0 and <=1 ? double max = mln_min(double); mln_piter(image2d<T>) it(trans_im.domain()); - for_all(it) if (std::norm(trans_im(it)) > max) max = std::norm(trans_im(it)); + const unsigned nrows = trans_im.nrows(); + const unsigned ncols = trans_im.ncols(); + image2d<R> new_im(trans_im.domain()); if (ordered) for (unsigned row = 0; row < new_im.nrows(); ++row) for (unsigned col = 0; col < new_im.ncols(); ++col) - { - if (std::norm(opt::at(trans_im, (row + trans_im.nrows() / 2) % trans_im.nrows(), - (col + trans_im.ncols() / 2) % - trans_im.ncols())) >= max * clip) - opt::at(new_im, row, col) = mln_max(R); - else - opt::at(new_im, row, col) = - (double) mln_max(R) * - std::norm(opt::at(trans_im, (row + trans_im.nrows() / 2) % trans_im.nrows(), - (col + trans_im.ncols() / 2) % - trans_im.ncols())) / (max * clip); - } - else - { - for_all(it) - { - if (std::norm(trans_im(it)) >= max * clip) - new_im(it) = mln_max(R); + if (std::norm(opt::at(trans_im, + (row + nrows / 2) % nrows, + (col + ncols / 2) % ncols)) + >= max * clip) + opt::at(new_im, row, col) = mln_max(R); else - new_im(it) = (double) mln_max(R) * - std::norm(trans_im(it)) / (max * clip); - } - } - + opt::at(new_im, row, col) = + (double) mln_max(R) * + std::norm(opt::at(trans_im, + (row + nrows / 2) % nrows, + (col + ncols / 2) % ncols)) / (max * clip); + else + for_all(it) + if (std::norm(trans_im(it)) >= max * clip) + new_im(it) = mln_max(R); + else + new_im(it) = + (double) mln_max(R) * std::norm(trans_im(it)) / (max * clip); return new_im; } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a clipped value of |T[p]|.\n - ** - ** \param clip Value used for clipping. - ** \param ordered Kind of traversal. - */ + /// \brief Accessor to the transformed image (clipped + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a clipped value of <tt>|T[p]|</tt> is returned. + /// + /// \param clip Value used for clipping. + /// \param ordered Kind of traversal. image2d<T> transformed_image_clipped_magn(double clip, bool ordered = true) const { return transformed_image_clipped_magn<T>(clip, ordered); } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a clipped value of |T[p]|.\n - ** - ** \param R Data type of the resulting image. - ** - ** \param ordered Kind of traversal. - */ - - image2d<T> transformed_image_clipped_magn(bool ordered = true) const - { - return transformed_image_clipped_magn<T>(1, ordered); - } - - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a clipped value of |T[p]|.\n - ** - ** \param R Data type of the resulting image. - ** - ** \param ordered Kind of traversal. - */ - + /// \brief Accessor to the transformed image (clipped + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a clipped value of <tt>|T[p]|</tt> is returned. + /// + /// \tparam R Value type of the resulting image. + /// + /// \param ordered Kind of traversal. template <class R> image2d<R> transformed_image_clipped_magn(bool ordered = true) const { return transformed_image_clipped_magn<R>(1, ordered); } - // FIXME: Find a more elegant way to fix range interval on a and b. - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a log translated value of |T[p]| on interval [a; b].\n - ** - ** \param a Lower bound. - ** \param b Upper bound. - ** \param ordered Kind of traversal. - */ + /// \brief Accessor to the transformed image (clipped + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a clipped value of <tt>|T[p]|</tt> is returned. + /// + /// \param ordered Kind of traversal. + image2d<T> transformed_image_clipped_magn(bool ordered = true) const + { + return transformed_image_clipped_magn<T>(1, ordered); + } + /// \brief Accessor to the transformed image (log of the + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a log value of <tt>|T[p]|</tt> translated in the + /// interval [a, b]. + /// + /// \tparam R Value type of the resulting image. + /// + /// \param a Lower bound. + /// \param b Upper bound. + /// \param ordered Kind of traversal. template <class R> - image2d<R> transformed_image_log_magn(double a, - double b, + image2d<R> transformed_image_log_magn(double a, double b, bool ordered = true) const { - // Check that R is real - // 0 <= a <= 1000 - // 0 <= b <= 1000 + /* FIXME: Find a more elegant way to fix range interval on a + and b (Note from Roland: what does it mean?). */ + + // FIXME: Ensure R is real. + // FIXME: Ensure 0 <= a <= 1000. + // FIXME: Ensure 0 <= b <= 1000. image2d<R> new_im(trans_im.domain()); double max = mln_min(double); mln_piter(image2d<R>) it(trans_im.domain()); - for_all(it) if (std::norm(trans_im(it)) > max) max = std::norm(trans_im(it)); - + const unsigned nrows = trans_im.nrows(); + const unsigned ncols = trans_im.ncols(); if (ordered) for (unsigned row = 0; row < new_im.nrows(); ++row) for (unsigned col = 0; col < new_im.ncols(); ++col) opt::at(new_im, row, col) = - log(a + b * std::norm(opt::at(trans_im, (row + trans_im.nrows() / 2) % trans_im.nrows(), - (col + trans_im.ncols() / 2) % trans_im.ncols()))) / - log (a + b * max) * mln_max(R); + log(a + b * std::norm(opt::at(trans_im, + (row + nrows / 2) % nrows, + (col + ncols / 2) % ncols))) + / log (a + b * max) * mln_max(R); else { mln_piter(image2d< std::complex<T> >) it(trans_im.domain()); - for_all(it) - new_im(it) = log(a + b * std::norm(trans_im(it))) / - log (a + b * max) * mln_max(R); + new_im(it) = + log(a + b * std::norm(trans_im(it))) + / log (a + b * max) * mln_max(R); } - return new_im; } - // FIXME: Find a more elegant way to fix boundaries of a and b. - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a log translated value of |T[p]| on interval [a; b].\n - ** - ** \param a Lower bound. - ** \param b Upper bound. - ** \param ordered Kind of traversal. - */ - - image2d<T> transformed_image_log_magn(double a, - double b, - bool ordered = true) const + /// \brief Accessor to the transformed image (log of the + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a log value of <tt>|T[p]|</tt> translated in the + /// interval [a, b]. + /// + /// \param a Lower bound. + /// \param b Upper bound. + /// \param ordered Kind of traversal. + image2d<T> transformed_image_log_magn(double a, double b, + bool ordered = true) const { return transformed_image_log_magn<T>(a, b, ordered); } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a log translated value of |T[p]| on interval [1; 100].\n - ** - ** \param R Data type of the resulting image. - ** - ** \param ordered Kind of traversal. - */ - + /// \brief Accessor to the transformed image (log of the + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a log value of <tt>|T[p]|</tt> translated in the + /// interval [1, 100]. + /// + /// \tparam R Value type of the resulting image. + /// + /// \param ordered Kind of traversal. template <class R> image2d<R> transformed_image_log_magn(bool ordered = true) const { return transformed_image_log_magn<R>(1, 100, ordered); } - /*! - ** \brief Accessor to transformed image. - ** - ** For each point p of the transformed image T, you get - ** a log translated value of |T[p]| on interval [1; 100].\n - ** - ** \param ordered Kind of traversal. - */ - + /// \brief Accessor to the transformed image (log of the + /// magnitude). + /// + /// For each point \p p of the transformed image \p T, an image + /// containing a log value of <tt>|T[p]|</tt> translated in the + /// interval [1, 100]. + /// + /// \param ordered Kind of traversal. image2d<T> transformed_image_log_magn(bool ordered = true) const { return transformed_image_log_magn<T>(1, 100, ordered); } - - /*! - ** \brief Destructor. - ** - ** Let memory free for other big images !!! - */ - ~_fft() + ~fft() { fftw_free(in); fftw_free(out); @@ -363,218 +329,222 @@ namespace mln { } protected: - - typename fft_trait<T>::fftw_input *in; ///< Input image. - std::complex<T> *out; ///< Complex image. - fftw_plan p; ///< Plan. - fftw_plan p_inv; ///< inverted plan. - image2d< std::complex<T> > trans_im; ///< Transformed image. - + /// Input image (used internally by FFTW). + typename fft_trait<T>::fftw_input* in; + /// Output (complex) image used internally by FFTW). + std::complex<T>* out; + /// (Forward) plan (command to be executed by FFTW). + fftw_plan p; + /// Inverse (backward) plan (command to be executed by FFTW). + fftw_plan p_inv; + /// Transformed image (``exported'' Milena image accessible + /// through accessors). + image2d< std::complex<T> > trans_im; }; - } // end of namespace internal + } // end of namespace mln::internal - namespace transform { - /*! - ** \brief fft class declaration. - ** - ** \param T Data type. - ** \param which Dispatch. - */ + namespace transform + { + + /// \brief FFT engine, producing a Discrete Fourier Transform + /// using FFTW (version 3). + /// + /// \tparam T Data type. + /// + /// \param which Dispatch traits. template <class T, internal::fft_dispatch which = internal::fft_trait<T>::which > class fft; - /*! - ** \brief fft specialization for fft real dispatch. - ** - ** \param T Data type. - */ + + /// \brief FFT engine (specialization for images of real values). + /// + /// \tparam T Data type. template <class T> - class fft<T, internal::fft_real> : public internal::_fft<T> + class fft<T, internal::fft_real> : public internal::fft<T> { - public: - - /*! - ** \brief Constructor. - ** - ** Initialization of data in order to compute the fft. - ** - ** \param original_im Image to process. - */ + /// \brief Constructor. + /// + /// Initialization of data for the computation of the FFT. + /// + /// \param original_im Image to process. template <typename D> fft(const image2d<D>& original_im) { - this->in = (T*) fftw_malloc(original_im.nrows() * original_im.ncols() * sizeof(T)); - this->out = (std::complex<T>*) - fftw_malloc(original_im.nrows() * (original_im.ncols() / 2 + 1) * sizeof(std::complex<T>)); - - for (unsigned row = 0; row < original_im.nrows(); ++row) - for (unsigned col = 0; col < original_im.ncols(); ++col) - this->in[row * original_im.ncols() + col] = opt::at(original_im, row, col); - - this->p = fftw_plan_dft_r2c_2d (original_im.nrows(), original_im.ncols(), - this->in, reinterpret_cast<fftw_complex*>(this->out), FFTW_ESTIMATE); - this->p_inv = fftw_plan_dft_c2r_2d (original_im.nrows(), original_im.ncols(), - reinterpret_cast<fftw_complex*>(this->out), this->in, FFTW_ESTIMATE); - + const unsigned nrows = original_im.nrows(); + const unsigned ncols = original_im.ncols(); + + this->in = (T*) fftw_malloc(nrows * ncols * sizeof(T)); + this->out = (std::complex<T>*) fftw_malloc(nrows + * (ncols / 2 + 1) + * sizeof(std::complex<T>)); + + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) + this->in[row * ncols + col] = + opt::at(original_im, row, col); + + this->p = + fftw_plan_dft_r2c_2d (nrows, ncols, + this->in, + reinterpret_cast<fftw_complex*>(this->out), + FFTW_ESTIMATE); + this->p_inv = + fftw_plan_dft_c2r_2d (nrows, ncols, + reinterpret_cast<fftw_complex*>(this->out), + this->in, + FFTW_ESTIMATE); this->trans_im = image2d< std::complex<T> >(original_im.domain()); } - /*! - ** \brief Compute and return the transform. - */ + /// \brief Compute and return the transform (as a complex image). image2d< std::complex<T> > transform() { fftw_execute(this->p); - unsigned denom = this->trans_im.nrows() * this->trans_im.ncols(); + const unsigned nrows = this->trans_im.nrows(); + const unsigned ncols = this->trans_im.ncols(); + unsigned denom = nrows * ncols; int i = 0; - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col <= this->trans_im.ncols() / 2; ++col) + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col <= ncols / 2; ++col) { - this->out[i] = std::complex<T> (this->out[i].real() / denom, this->out[i].imag() / denom); + this->out[i] = std::complex<T> (this->out[i].real() / denom, + this->out[i].imag() / denom); opt::at(this->trans_im, row, col) = this->out[i]; ++i; } - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = this->trans_im.ncols() - 1; col > this->trans_im.ncols() / 2; --col) - opt::at(this->trans_im, row, col) = opt::at(this->trans_im, this->trans_im.nrows() - row - 1, - this->trans_im.ncols() - col - 1); + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = ncols - 1; col > ncols / 2; --col) + opt::at(this->trans_im, row, col) = + opt::at(this->trans_im, nrows - row - 1, ncols - col - 1); return this->trans_im; } - /*! - ** \brief Compute and return the invert transform. - ** - ** \param R Data type of output image. - */ + /// \brief Compute and return the inverse transform (as a real + /// image) of the FFT. + /// + /// \tparam R Value type of output image. template <class R> image2d<R> transform_inv() { - // FIXME : Check that R is real + // FIXME: Ensure R is real. - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col <= this->trans_im.ncols() / 2; ++col) - this->out[row * (this->trans_im.ncols() / 2 + 1) + col] = + const unsigned nrows = this->trans_im.nrows(); + const unsigned ncols = this->trans_im.ncols(); + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col <= ncols / 2; ++col) + this->out[row * (ncols / 2 + 1) + col] = opt::at(this->trans_im, row, col); fftw_execute(this->p_inv); image2d<R> new_im(this->trans_im.domain()); int i = 0; - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col < this->trans_im.ncols(); ++col) + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) { - opt::at(new_im, row, col) = (this->in[i] >= mln_min(R) ? - (this->in[i] <= mln_max(R) ? - (R)this->in [i] : - mln_min(R)) : - mln_max(R)); + opt::at(new_im, row, col) = (this->in[i] >= mln_min(R) + ? (this->in[i] <= mln_max(R) + ? (R) this->in [i] + : mln_min(R)) + : mln_max(R)); ++i; } return new_im; } - /*! - ** \brief Compute and return the invert transform. - */ + /// \brief Compute and return the inverse transform of the FFT. image2d<T> transform_inv() { return transform_inv<T>(); } - }; - /*! - ** \brief fft specialization for fft complex dispatch. - ** - ** \param T Data type. - ** \param R Complex representation kind. - */ + + /// \brief FFT engine (specialization for images of complex values). + /// + /// \tparam T Data type. template <class T> - class fft<T, internal::fft_cplx> : public internal::_fft<T> + class fft<T, internal::fft_cplx> : public internal::fft<T> { - public: - - /*! - ** \brief Constructor. - ** - ** Initialization of data in order to compute the fft. - ** - ** \param original_im Image to process. - */ + /// \brief Constructor. + /// + /// Initialization of data for the computation of the FFT. + /// + /// \param original_im Image to process. fft(const image2d< std::complex<T> >& original_im) { - this->in = fftw_malloc(sizeof(std::complex<T>) * - original_im.nrows() * original_im.ncols()); - this->out = fftw_malloc(sizeof(std::complex<T>) * - original_im.nrows() * original_im.ncols()); + const unsigned nrows = original_im.nrows(); + const unsigned ncols = original_im.ncols(); + + this->in = fftw_malloc(sizeof(std::complex<T>) * nrows * ncols); + this->out = fftw_malloc(sizeof(std::complex<T>) * nrows * ncols); - for (unsigned row = 0; row < original_im.nrows(); ++row) - for (unsigned col = 0; col < original_im.ncols(); ++col) + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) { - this->in[row * original_im.ncols() + col].re = - original_im(row, col).real(); - this->in[row * original_im.ncols() + col].im = - original_im(row, col).imag(); + this->in[row * ncols + col].re = original_im(row, col).real(); + this->in[row * ncols + col].im = original_im(row, col).imag(); } - this->p = fftw_plan_dft_2d(original_im.nrows(), original_im.ncols(), - this->in, this->out, - FFTW_FORWARD, FFTW_ESTIMATE); - this->p_inv = fftw_plan_dft_2d(original_im.nrows(), original_im.ncols(), - this->out, this->in, + this->p = fftw_plan_dft_2d(nrows, ncols, this->in, this->out, + FFTW_FORWARD, FFTW_ESTIMATE); + this->p_inv = fftw_plan_dft_2d(nrows, ncols, this->out, this->in, FFTW_BACKWARD, FFTW_ESTIMATE); - this->trans_im = image2d< std::complex<T> >(original_im.domain()); } - /*! - ** \brief Compute and return the transform. - */ + /// \brief Compute and return the transform (as a complex image). image2d< std::complex<T> > transform() { fftw_execute(this->p); - unsigned denom = this->trans_im.nrows() * this->trans_im.ncols(); + const unsigned nrows = this->trans_im.nrows(); + const unsigned ncols = this->trans_im.ncols(); + unsigned denom = nrows * ncols; int i = 0; - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col < this->trans_im.ncols(); ++col) + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) { this->out[i].re /= denom; this->out[i].im /= denom; - this->trans_im(row, col) = std::complex<double>(this->out[i].re, - this->out[i].im); + this->trans_im(row, col) = + std::complex<double>(this->out[i].re, this->out[i].im); ++i; } return this->trans_im; } - /*! - ** \brief Compute and return the invert transform. - ** - ** \param R Data type of output image. - */ + /// \brief Compute and return the inverse transform (as a + /// complex image). + /// + /// \tparam R Component type of the value type of the output + /// image. template <class R> image2d< std::complex<R> > transform_inv() { - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col < this->trans_im.ncols(); ++col) + const unsigned nrows = this->trans_im.nrows(); + const unsigned ncols = this->trans_im.ncols(); + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) { - this->out[row * this->trans_im.ncols() + col].re = this->trans_im(row, col).real(); - this->out[row * this->trans_im.ncols() + col].im = this->trans_im(row, col).imag(); + this->out[row * ncols + col].re = + this->trans_im(row, col).real(); + this->out[row * ncols + col].im = + this->trans_im(row, col).imag(); } fftw_execute(this->p_inv); image2d< std::complex<R> > new_im(this->trans_im.size()); int i = 0; - for (unsigned row = 0; row < this->trans_im.nrows(); ++row) - for (unsigned col = 0; col < this->trans_im.ncols(); ++col) + for (unsigned row = 0; row < nrows; ++row) + for (unsigned col = 0; col < ncols; ++col) { new_im(row, col) = this->in[i]; ++i; @@ -582,9 +552,7 @@ namespace mln { return new_im; } - /*! - ** \brief Compute and return the invert transform. - */ + /// \brief Compute and return the inverse transform of the FFT. image2d< std::complex<T> > transform_inv() { return transform_inv<T>(); @@ -592,8 +560,8 @@ namespace mln { }; - } // end of namespace transform + } // end of namespace mln::transform -} // end of namespace oln +} // end of namespace mln #endif // ! MLN_TRANSFORM_FFT_HH -- 1.7.2.5