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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Covered Software is provided under this License on an "as is"
* basis, without warranty of any kind, either expressed, implied, or
* statutory, including, without limitation, warranties that the
* Covered Software is free of defects, merchantable, fit for a
* particular purpose or non-infringing.
* See the Mozilla Public License v. 2.0 for more details.
*
* For more details, see http://www.mrtrix.org/.
*/
#ifndef __interp_sinc_h__
#define __interp_sinc_h__
#include "types.h"
#include "interp/base.h"
#include "math/sinc.h"
#define SINC_WINDOW_SIZE 7
namespace MR
{
namespace Interp
{
//! \addtogroup interp
// @{
//! This class provides access to the voxel intensities of an image, using sinc interpolation.
/*! Interpolation is only performed along the first 3 (spatial) axes.
* The (integer) position along the remaining axes should be set using the
* template Image class.
* The spatial coordinates can be set using the functions voxel(), image(),
* and scanner().
* For example:
* \code
* auto input = Image<float>::create (Argument[0]);
*
* // create an Interp::Sinc object using input as the parent data set:
* Interp::Sinc<decltype(input) > interp (input);
*
* // set the scanner-space position to [ 10.2 3.59 54.1 ]:
* interp.scanner (10.2, 3.59, 54.1);
*
* // get the value at this position:
* float value = interp.value();
* \endcode
*
* The template \a input class must be usable with this type of syntax:
* \code
* int xsize = input.size(0); // return the dimension
* int ysize = input.size(1); // along the x, y & z dimensions
* int zsize = input.size(2);
* float v[] = { input.spacing(0), input.spacing(1), input.spacing(2) }; // return voxel dimensions
* input.index(0) = 0; // these lines are used to
* input.index(1)--; // set the current position
* input.index(2)++; // within the data set
* float f = input.value();
* transform_type M = input.transform(); // a valid 4x4 transformation matrix
* \endcode
*/
template <class ImageType> class Sinc : public Base<ImageType>
{ MEMALIGN(Sinc<ImageType>)
public:
using typename Base<ImageType>::value_type;
using Base<ImageType>::out_of_bounds;
using Base<ImageType>::out_of_bounds_value;
Sinc (const ImageType& parent, value_type value_when_out_of_bounds = Base<ImageType>::default_out_of_bounds_value(), const size_t w = SINC_WINDOW_SIZE) :
Base<ImageType> (parent, value_when_out_of_bounds),
window_size (w),
kernel_width ((window_size-1)/2),
Sinc_x (w),
Sinc_y (w),
Sinc_z (w),
y_values (w, 0.0),
z_values (w, 0.0)
{
assert (w % 2);
}
//! Set the current position to <b>voxel space</b> position \a pos
/*! See file interp/base.h for details. */
template <class VectorType>
bool voxel (const VectorType& pos) {
if (Base<ImageType>::set_out_of_bounds (pos))
return false;
Sinc_x.set (*this, 0, pos[0]);
Sinc_y.set (*this, 1, pos[1]);
Sinc_z.set (*this, 2, pos[2]);
return true;
}
//! Set the current position to <b>image space</b> position \a pos
/*! See file interp/base.h for details. */
template <class VectorType>
FORCE_INLINE bool image (const VectorType& pos) {
return voxel (Transform::voxelsize.inverse() * pos.template cast<default_type>());
}
//! Set the current position to the <b>scanner space</b> position \a pos
/*! See file interp/base.h for details. */
template <class VectorType>
FORCE_INLINE bool scanner (const VectorType& pos) {
return voxel (Transform::scanner2voxel * pos.template cast<default_type>());
}
//! Read an interpolated image value from the current position.
/*! See file interp/base.h for details. */
FORCE_INLINE value_type value () {
if (out_of_bounds)
return out_of_bounds_value;
for (size_t z = 0; z != window_size; ++z) {
ImageType::index(2) = Sinc_z.index (z);
for (size_t y = 0; y != window_size; ++y) {
ImageType::index(1) = Sinc_y.index (y);
// Cast necessary so that Sinc_x calls the ImageType value() function
y_values[y] = Sinc_x.value (static_cast<ImageType&>(*this), 0);
}
z_values[z] = Sinc_y.value (y_values);
}
return Sinc_z.value (z_values);
}
//! Read interpolated values from volumes along axis >= 3
/*! See file interp/base.h for details. */
Eigen::Matrix<value_type, Eigen::Dynamic, 1> row (size_t axis) {
assert (axis > 2);
assert (axis < ImageType::ndim());
if (out_of_bounds) {
Eigen::Matrix<value_type, Eigen::Dynamic, 1> out_of_bounds_row (ImageType::size(axis));
out_of_bounds_row.setOnes();
out_of_bounds_row *= out_of_bounds_value;
return out_of_bounds_row;
}
Eigen::Matrix<value_type, Eigen::Dynamic, 1> row (ImageType::size(axis));
// Lazy, non-optimized code, since nothing is actually using this yet
// Just make use of the kernel setup within voxel()
for (ssize_t volume = 0; volume != ImageType::size(axis); ++volume) {
ImageType::index (axis) = volume;
row (volume,0) = value();
}
return row;
}
protected:
const size_t window_size;
const int kernel_width;
Math::Sinc<value_type> Sinc_x, Sinc_y, Sinc_z;
vector<value_type> y_values, z_values;
};
template <class ImageType, typename... Args>
inline Sinc<ImageType> make_sinc (const ImageType& parent, Args&&... args) {
return Sinc<ImageType> (parent, std::forward<Args> (args)...);
}
//! @}
}
}
#endif
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