//
// Copyright 2005-2007 Adobe Systems Incorporated
+// Copyright 2019 Miral Shah <miralshah2211@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
namespace boost { namespace gil {
-// 2D seperable convolutions and correlations
-
-/// \ingroup ImageAlgorithms
-/// Boundary options for 1D correlations/convolutions
-enum convolve_boundary_option {
- convolve_option_output_ignore, /// do nothing to the output
- convolve_option_output_zero, /// set the output to zero
- convolve_option_extend_padded, /// assume the source boundaries to be padded already
- convolve_option_extend_zero, /// assume the source boundaries to be zero
- convolve_option_extend_constant /// assume the source boundaries to be the boundary value
-};
+// 2D spatial seperable convolutions and cross-correlations
namespace detail {
-/// compute the correlation of 1D kernel with the rows of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView,typename Correlator>
-void correlate_rows_imp(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option,
- Correlator correlator) {
- BOOST_ASSERT(src.dimensions() == dst.dimensions());
- BOOST_ASSERT(ker.size() != 0);
-
- using PIXEL_SRC_REF = typename pixel_proxy<typename SrcView::value_type>::type;
- using PIXEL_DST_REF = typename pixel_proxy<typename DstView::value_type>::type;
-
- if(ker.size()==1) {//reduces to a multiplication
- view_multiplies_scalar<PixelAccum>(src,*ker.begin(),dst);
+
+/// \brief Compute the cross-correlation of 1D kernel with the rows of an image
+/// \tparam PixelAccum - TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel - TODO
+/// \tparam DstView Models MutableImageViewConcept
+/// \tparam Correlator - TODO
+/// \param src_view
+/// \param kernel - TODO
+/// \param dst_view Destination where new computed values of pixels are assigned to
+/// \param option - TODO
+/// \param correlator - TODO
+template
+<
+ typename PixelAccum,
+ typename SrcView,
+ typename Kernel,
+ typename DstView,
+ typename Correlator
+>
+void correlate_rows_impl(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option,
+ Correlator correlator)
+{
+ BOOST_ASSERT(src_view.dimensions() == dst_view.dimensions());
+ BOOST_ASSERT(kernel.size() != 0);
+
+ if(kernel.size() == 1)
+ {
+ // Reduces to a multiplication
+ view_multiplies_scalar<PixelAccum>(src_view, *kernel.begin(), dst_view);
return;
}
- int width=src.width(),height=src.height();
- PixelAccum acc_zero; pixel_zeros_t<PixelAccum>()(acc_zero);
- if (width==0) return;
- if (option==convolve_option_output_ignore || option==convolve_option_output_zero) {
- typename DstView::value_type dst_zero; pixel_assigns_t<PixelAccum,PIXEL_DST_REF>()(acc_zero,dst_zero);
- if (width<(int)ker.size()) {
- if (option==convolve_option_output_zero)
- fill_pixels(dst,dst_zero);
- } else {
+ using src_pixel_ref_t = typename pixel_proxy<typename SrcView::value_type>::type;
+ using dst_pixel_ref_t = typename pixel_proxy<typename DstView::value_type>::type;
+ using x_coord_t = typename SrcView::x_coord_t;
+ using y_coord_t = typename SrcView::y_coord_t;
+
+ x_coord_t const width = src_view.width();
+ y_coord_t const height = src_view.height();
+ if (width == 0)
+ return;
+
+ PixelAccum acc_zero;
+ pixel_zeros_t<PixelAccum>()(acc_zero);
+ if (option == boundary_option::output_ignore || option == boundary_option::output_zero)
+ {
+ typename DstView::value_type dst_zero;
+ pixel_assigns_t<PixelAccum, dst_pixel_ref_t>()(acc_zero, dst_zero);
+ if (width < static_cast<x_coord_t>(kernel.size()))
+ {
+ if (option == boundary_option::output_zero)
+ fill_pixels(dst_view, dst_zero);
+ }
+ else
+ {
std::vector<PixelAccum> buffer(width);
- for(int rr=0;rr<height;++rr) {
- assign_pixels(src.row_begin(rr),src.row_end(rr),&buffer.front());
- typename DstView::x_iterator it_dst=dst.row_begin(rr);
- if (option==convolve_option_output_zero)
- std::fill_n(it_dst,ker.left_size(),dst_zero);
- it_dst+=ker.left_size();
- correlator(&buffer.front(),&buffer.front()+width+1-ker.size(),
- ker.begin(),it_dst);
- it_dst+=width+1-ker.size();
- if (option==convolve_option_output_zero)
- std::fill_n(it_dst,ker.right_size(),dst_zero);
+ for (y_coord_t y = 0; y < height; ++y)
+ {
+ assign_pixels(src_view.row_begin(y), src_view.row_end(y), &buffer.front());
+ typename DstView::x_iterator it_dst = dst_view.row_begin(y);
+ if (option == boundary_option::output_zero)
+ std::fill_n(it_dst, kernel.left_size(), dst_zero);
+ it_dst += kernel.left_size();
+ correlator(&buffer.front(), &buffer.front() + width + 1 - kernel.size(),
+ kernel.begin(), it_dst);
+ it_dst += width + 1 - kernel.size();
+ if (option == boundary_option::output_zero)
+ std::fill_n(it_dst, kernel.right_size(), dst_zero);
}
}
- } else {
- std::vector<PixelAccum> buffer(width+ker.size()-1);
- for(int rr=0;rr<height;++rr) {
- PixelAccum* it_buffer=&buffer.front();
- if (option==convolve_option_extend_padded) {
- assign_pixels(src.row_begin(rr)-ker.left_size(),
- src.row_end(rr)+ker.right_size(),
- it_buffer);
- } else if (option==convolve_option_extend_zero) {
- std::fill_n(it_buffer,ker.left_size(),acc_zero);
- it_buffer+=ker.left_size();
- assign_pixels(src.row_begin(rr),src.row_end(rr),it_buffer);
- it_buffer+=width;
- std::fill_n(it_buffer,ker.right_size(),acc_zero);
- } else if (option==convolve_option_extend_constant) {
+ }
+ else
+ {
+ std::vector<PixelAccum> buffer(width + kernel.size() - 1);
+ for (y_coord_t y = 0; y < height; ++y)
+ {
+ PixelAccum *it_buffer = &buffer.front();
+ if (option == boundary_option::extend_padded)
+ {
+ assign_pixels(
+ src_view.row_begin(y) - kernel.left_size(),
+ src_view.row_end(y) + kernel.right_size(),
+ it_buffer);
+ }
+ else if (option == boundary_option::extend_zero)
+ {
+ std::fill_n(it_buffer, kernel.left_size(), acc_zero);
+ it_buffer += kernel.left_size();
+ assign_pixels(src_view.row_begin(y), src_view.row_end(y), it_buffer);
+ it_buffer += width;
+ std::fill_n(it_buffer, kernel.right_size(), acc_zero);
+ }
+ else if (option == boundary_option::extend_constant)
+ {
PixelAccum filler;
- pixel_assigns_t<PIXEL_SRC_REF,PixelAccum>()(*src.row_begin(rr),filler);
- std::fill_n(it_buffer,ker.left_size(),filler);
- it_buffer+=ker.left_size();
- assign_pixels(src.row_begin(rr),src.row_end(rr),it_buffer);
- it_buffer+=width;
- pixel_assigns_t<PIXEL_SRC_REF,PixelAccum>()(src.row_end(rr)[-1],filler);
- std::fill_n(it_buffer,ker.right_size(),filler);
+ pixel_assigns_t<src_pixel_ref_t, PixelAccum>()(*src_view.row_begin(y), filler);
+ std::fill_n(it_buffer, kernel.left_size(), filler);
+ it_buffer += kernel.left_size();
+ assign_pixels(src_view.row_begin(y), src_view.row_end(y), it_buffer);
+ it_buffer += width;
+ pixel_assigns_t<src_pixel_ref_t, PixelAccum>()(src_view.row_end(y)[-1], filler);
+ std::fill_n(it_buffer, kernel.right_size(), filler);
}
- correlator(&buffer.front(),&buffer.front()+width,
- ker.begin(),
- dst.row_begin(rr));
+
+ correlator(
+ &buffer.front(), &buffer.front() + width,
+ kernel.begin(),
+ dst_view.row_begin(y));
}
}
}
+
template <typename PixelAccum>
-class correlator_n {
-private:
- std::size_t _size;
+class correlator_n
+{
public:
- correlator_n(std::size_t size_in) : _size(size_in) {}
- template <typename SrcIterator,typename KernelIterator,typename DstIterator>
- void operator()(SrcIterator src_begin,SrcIterator src_end,
- KernelIterator ker_begin,
- DstIterator dst_begin) {
- correlate_pixels_n<PixelAccum>(src_begin,src_end,ker_begin,_size,dst_begin);
+ correlator_n(std::size_t size) : size_(size) {}
+
+ template <typename SrcIterator, typename KernelIterator, typename DstIterator>
+ void operator()(
+ SrcIterator src_begin,
+ SrcIterator src_end,
+ KernelIterator kernel_begin,
+ DstIterator dst_begin)
+ {
+ correlate_pixels_n<PixelAccum>(src_begin, src_end, kernel_begin, size_, dst_begin);
}
+
+private:
+ std::size_t size_{0};
};
-template <std::size_t Size,typename PixelAccum>
-struct correlator_k {
-public:
- template <typename SrcIterator,typename KernelIterator,typename DstIterator>
- void operator()(SrcIterator src_begin,SrcIterator src_end,
- KernelIterator ker_begin,
- DstIterator dst_begin){
- correlate_pixels_k<Size,PixelAccum>(src_begin,src_end,ker_begin,dst_begin);
+
+template <std::size_t Size, typename PixelAccum>
+struct correlator_k
+{
+ template <typename SrcIterator, typename KernelIterator, typename DstIterator>
+ void operator()(
+ SrcIterator src_begin,
+ SrcIterator src_end,
+ KernelIterator kernel_begin,
+ DstIterator dst_begin)
+ {
+ correlate_pixels_k<Size, PixelAccum>(src_begin, src_end, kernel_begin, dst_begin);
}
};
+
} // namespace detail
/// \ingroup ImageAlgorithms
-///correlate a 1D variable-size kernel along the rows of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Correlate 1D variable-size kernel along the rows of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void correlate_rows(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- detail::correlate_rows_imp<PixelAccum>(src,ker,dst,option,detail::correlator_n<PixelAccum>(ker.size()));
+void correlate_rows(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ detail::correlate_rows_impl<PixelAccum>(
+ src_view, kernel, dst_view, option, detail::correlator_n<PixelAccum>(kernel.size()));
}
/// \ingroup ImageAlgorithms
-///correlate a 1D variable-size kernel along the columns of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Correlate 1D variable-size kernel along the columns of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void correlate_cols(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- correlate_rows<PixelAccum>(transposed_view(src),ker,transposed_view(dst),option);
+void correlate_cols(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ correlate_rows<PixelAccum>(
+ transposed_view(src_view), kernel, transposed_view(dst_view), option);
}
/// \ingroup ImageAlgorithms
-///convolve a 1D variable-size kernel along the rows of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Convolve 1D variable-size kernel along the rows of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void convolve_rows(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- correlate_rows<PixelAccum>(src,reverse_kernel(ker),dst,option);
+void convolve_rows(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ correlate_rows<PixelAccum>(src_view, reverse_kernel(kernel), dst_view, option);
}
/// \ingroup ImageAlgorithms
-///convolve a 1D variable-size kernel along the columns of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Convolve 1D variable-size kernel along the columns of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void convolve_cols(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- convolve_rows<PixelAccum>(transposed_view(src),ker,transposed_view(dst),option);
+void convolve_cols(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ convolve_rows<PixelAccum>(
+ transposed_view(src_view), kernel, transposed_view(dst_view), option);
}
/// \ingroup ImageAlgorithms
-///correlate a 1D fixed-size kernel along the rows of an image
+/// \brief Correlate 1D fixed-size kernel along the rows of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void correlate_rows_fixed(const SrcView& src, const Kernel& kernel, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero)
+void correlate_rows_fixed(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
{
- using correlator = detail::correlator_k
- <
- std::extent<Kernel>::value,
- PixelAccum
- >;
- detail::correlate_rows_imp<PixelAccum>(
- src, kernel, dst, option, correlator{});
+ using correlator = detail::correlator_k<Kernel::static_size, PixelAccum>;
+ detail::correlate_rows_impl<PixelAccum>(src_view, kernel, dst_view, option, correlator{});
}
/// \ingroup ImageAlgorithms
-///correlate a 1D fixed-size kernel along the columns of an image
+/// \brief Correlate 1D fixed-size kernel along the columns of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
BOOST_FORCEINLINE
-void correlate_cols_fixed(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- correlate_rows_fixed<PixelAccum>(transposed_view(src),ker,transposed_view(dst),option);
+void correlate_cols_fixed(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ correlate_rows_fixed<PixelAccum>(
+ transposed_view(src_view), kernel, transposed_view(dst_view), option);
}
/// \ingroup ImageAlgorithms
-///convolve a 1D fixed-size kernel along the rows of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Convolve 1D fixed-size kernel along the rows of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void convolve_rows_fixed(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- correlate_rows_fixed<PixelAccum>(src,reverse_kernel(ker),dst,option);
+void convolve_rows_fixed(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ correlate_rows_fixed<PixelAccum>(src_view, reverse_kernel(kernel), dst_view, option);
}
/// \ingroup ImageAlgorithms
-///convolve a 1D fixed-size kernel along the columns of an image
-template <typename PixelAccum,typename SrcView,typename Kernel,typename DstView>
+/// \brief Convolve 1D fixed-size kernel along the columns of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
BOOST_FORCEINLINE
-void convolve_cols_fixed(const SrcView& src, const Kernel& ker, const DstView& dst,
- convolve_boundary_option option=convolve_option_extend_zero) {
- convolve_rows_fixed<PixelAccum>(transposed_view(src),ker,transposed_view(dst),option);
+void convolve_cols_fixed(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ convolve_rows_fixed<PixelAccum>(
+ transposed_view(src_view), kernel, transposed_view(dst_view), option);
+}
+
+namespace detail
+{
+
+/// \ingroup ImageAlgorithms
+/// \brief Convolve 1D variable-size kernel along both rows and columns of image
+/// \tparam PixelAccum TODO
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename PixelAccum, typename SrcView, typename Kernel, typename DstView>
+BOOST_FORCEINLINE
+void convolve_1d(
+ SrcView const& src_view,
+ Kernel const& kernel,
+ DstView const& dst_view,
+ boundary_option option = boundary_option::extend_zero)
+{
+ convolve_rows<PixelAccum>(src_view, kernel, dst_view, option);
+ convolve_cols<PixelAccum>(dst_view, kernel, dst_view, option);
+}
+
+template <typename SrcView, typename DstView, typename Kernel>
+void convolve_2d_impl(SrcView const& src_view, DstView const& dst_view, Kernel const& kernel)
+{
+ int flip_ker_row, flip_ker_col, row_boundary, col_boundary;
+ float aux_total;
+ for (std::ptrdiff_t view_row = 0; view_row < src_view.height(); ++view_row)
+ {
+ for (std::ptrdiff_t view_col = 0; view_col < src_view.width(); ++view_col)
+ {
+ aux_total = 0.0f;
+ for (std::size_t kernel_row = 0; kernel_row < kernel.size(); ++kernel_row)
+ {
+ flip_ker_row = kernel.size() - 1 - kernel_row; // row index of flipped kernel
+
+ for (std::size_t kernel_col = 0; kernel_col < kernel.size(); ++kernel_col)
+ {
+ flip_ker_col = kernel.size() - 1 - kernel_col; // column index of flipped kernel
+
+ // index of input signal, used for checking boundary
+ row_boundary = view_row + (kernel.center_y() - flip_ker_row);
+ col_boundary = view_col + (kernel.center_x() - flip_ker_col);
+
+ // ignore input samples which are out of bound
+ if (row_boundary >= 0 && row_boundary < src_view.height() &&
+ col_boundary >= 0 && col_boundary < src_view.width())
+ {
+ aux_total +=
+ src_view(col_boundary, row_boundary) *
+ kernel.at(flip_ker_row, flip_ker_col);
+ }
+ }
+ }
+ dst_view(view_col, view_row) = aux_total;
+ }
+ }
+}
+
+/// \ingroup ImageAlgorithms
+/// \brief convolve_2d can only use convolve_option_extend_zero as convolve_boundary_option
+/// this is the default option and cannot be changed for now
+/// (In future there are plans to improve the algorithm and allow user to use other options as well)
+/// \tparam SrcView Models ImageViewConcept
+/// \tparam Kernel TODO
+/// \tparam DstView Models MutableImageViewConcept
+template <typename SrcView, typename DstView, typename Kernel>
+void convolve_2d(SrcView const& src_view, Kernel const& kernel, DstView const& dst_view)
+{
+ BOOST_ASSERT(src_view.dimensions() == dst_view.dimensions());
+ BOOST_ASSERT(kernel.size() != 0);
+
+ gil_function_requires<ImageViewConcept<SrcView>>();
+ gil_function_requires<MutableImageViewConcept<DstView>>();
+ static_assert(color_spaces_are_compatible
+ <
+ typename color_space_type<SrcView>::type,
+ typename color_space_type<DstView>::type
+ >::value, "Source and destination views must have pixels with the same color space");
+
+ for (std::size_t i = 0; i < src_view.num_channels(); i++)
+ {
+ detail::convolve_2d_impl(
+ nth_channel_view(src_view, i),
+ nth_channel_view(dst_view, i),
+ kernel
+ );
+ }
}
-}} // namespace boost::gil
+}}} // namespace boost::gil::detail
#endif
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