stir::FourierRebinning Class Reference

Class for Serial FORE Reconstruction. More...

#include "stir/recon_buildblock/FourierRebinning.h"

Inheritance diagram for stir::FourierRebinning:

Public Member Functions
void	set_defaults () override
	Set defaults before parsing.
	FourierRebinning ()
	default constructor calls set_defaults();
std::string	method_info () const override
	This method returns the type of the algorithm for the rebinning.
Succeeded	rebin () override
	This method creates a stack of 2D rebinned sinograms from the whole 3D data set (i.e. the ProjData data) and saves it.
void	set_kmin (int km)
	A set of get and set utility functions to access the rebinning parameters.
void	set_wmin (int wm)
void	set_deltamin (int dm)
void	set_kc (int kcc)
void	set_fore_debug_level (int fdebug)
int	get_kmin ()
int	get_wmin ()
int	get_deltamin ()
int	get_kc ()
int	get_fore_debug_level ()
Public Member Functions inherited from stir::RegisteredParsingObject< FourierRebinning, ProjDataRebinning, ProjDataRebinning >
std::string	get_registered_name () const override
	Returns Derived::registered_name.
std::string	parameter_info () override
	Returns a string with all parameters and their values, in a form suitable for parsing again.
Public Member Functions inherited from stir::ProjDataRebinning
	~ProjDataRebinning () override
	virtual destructor
void	set_max_segment_num_to_process (int ns)
int	get_max_segment_num_to_process () const
void	set_output_filename_prefix (const std::string &s)
std::string	get_output_filename_prefix () const
void	set_input_proj_data_sptr (const shared_ptr< ProjData > &)
	set projection data that will be rebinned
shared_ptr< ProjData >	get_proj_data_sptr ()
virtual Succeeded	set_up ()
	operations prior to the rebinning
Public Member Functions inherited from stir::TimedObject
void	reset_timers ()
	reset all timers kept by this object
void	stop_timers () const
	stop all timers kept by this object
void	start_timers (bool do_reset=false) const
	start all timers kept by this object
double	get_CPU_timer_value () const
	get current value of the CPU timer (since first use or last reset)
double	get_wall_clock_timer_value () const
	get current value of the wall-clock timer (since first use or last reset)
Public Member Functions inherited from stir::ParsingObject
	ParsingObject (const ParsingObject &)
ParsingObject &	operator= (const ParsingObject &)
bool	parse (std::istream &f)
bool	parse (const char *const filename)
void	ask_parameters ()

Static Public Attributes
static const char *const	registered_name = "FORE"
	Name which will be used when parsing a ProjDataRebinning object.

Protected Member Functions
bool	post_processing () override
	This will be called at the end of the parsing.
void	initialise_keymap () override
	Initialise all keywords.
bool	post_processing () override
	used to check acceptable parameter ranges, etc...
void	set_defaults () override
	Set defaults before parsing.
void	initialise_keymap () override
	Initialise all keywords.
virtual void	set_key_values ()
	This will be called before parsing or parameter_info is called.

Protected Attributes
int	kmin
	Smallest angular freq. index minimum 2 ( 1 is zero frequency)
int	wmin
	Smallest transax. freq. index minimum 2 ( 1 is zero frequency)
int	deltamin
	Delta max for small omega limiting delta for SSRB for small freq.
int	kc
	kc index for consistency
int	fore_debug_level
	fore_debug_level. Setting it to >0 will produce some debug information
std::string	output_filename_prefix
	file name for output projdata (should be without extension)
std::string	input_filename
	file name for input projdata
int	max_segment_num_to_process
	the maximum absolute segment number to use in the reconstruction
shared_ptr< ProjData >	proj_data_sptr
KeyParser	parser

Additional Inherited Members
Static Public Member Functions inherited from stir::RegisteredParsingObject< FourierRebinning, ProjDataRebinning, ProjDataRebinning >
static ProjDataRebinning *	read_from_stream (std::istream *)
	Construct a new object (of type Derived) by parsing the istream.
Static Public Member Functions inherited from stir::RegisteredObject< ProjDataRebinning >
static ProjDataRebinning *	read_registered_object (std::istream *in, const std::string &registered_name)
	Construct a new object (of a type derived from Root, its actual type determined by the registered_name parameter) by parsing the istream.
static ProjDataRebinning *	ask_type_and_parameters ()
	ask the user for the type, and then calls read_registered_object(0, type)
static void	list_registered_names (std::ostream &stream)
	List all possible registered names to the stream.
Protected Types inherited from stir::RegisteredObject< ProjDataRebinning >
typedef ProjDataRebinning *(*	RootFactory) (std::istream *)
	The type of a root factory is a function, taking an istream* as argument, and returning a Root*.
typedef FactoryRegistry< std::string, RootFactory, interfile_less >	RegistryType
	The type of the registry.
Static Protected Member Functions inherited from stir::RegisteredObject< ProjDataRebinning >
static RegistryType &	registry ()
	Static function returning the registry.

Detailed Description

Class for Serial FORE Reconstruction.

The digital implementation of the rebinning is done as follows:

a) Initialise the 2D Fourier transform of all rebinned sinograms Pr(w,k);
b) Process sequentially each pair of oblique sinograms pij and pji for i,j (= 0..2*num_rings-2) as:

• merge pij and pji to get a sinogram sampled over 2p;
  
• calculates the 2D FFT Pij(w,k) of the merged sinogram;
  
• assign each frequency component (w,k) to the rebinned sinogram of the slice lying closest axially to z - (tk/w): Pr(w,k) = Pr(w,k) + Pij(w,k), where r is the nearest integer to (i+j) - k(i-j)/wR;
  c) Normalise Pr(w,k) for the variable number of contributions to each w, k, r ;
  d) Calculate the 2D inverse FFT of each Pr(w,k) to get the rebinned sinogram Pr(s,f);

As FORE is based on a high frequency approximation, it is necessary to handle separately low and high frequencies. This is done by subdividing the (w,k) plane into three sub regions defined by two parameters in Fourier space, w (the continuous frequency corresponding to the radial coordinates s) and k (the integer Fourier index corresponding to the azimuthal angle f), and by applying in each region a different method to estimated the rebinned sinogram.

The rebinned data are represented in spatial space with |s|<=R, 0<=f<p, |z|<=L/2, where L is the length of the axial FOV and R the ring radius. In the high frequencies (region 1), the rebinned data are estimated using Fourier rebinning. In the second high frequency region (region 2), the consistency condition is not satisfied and hence all the rebinned data are forced to 0: Pr(w,k, z) = 0, when |k/w|>=R; |w|>wlim or |k|>klim. Finally, in the low-frequency (region 3), Fourier rebinning is not applicable. Therefore the rebinned data are estimated using only the oblique sinograms with a small value of d : dlim. Owing to the small value of d, the axial shift can be neglected as in the SSRB approximation.

Member Function Documentation

set_defaults()

void stir::FourierRebinning::set_defaults ( )

overridevirtual

Set defaults before parsing.

Reimplemented from stir::ParsingObject.

References deltamin, fore_debug_level, kc, kmin, set_defaults(), stir::ProjDataRebinning::set_defaults(), and wmin.

Referenced by FourierRebinning(), and set_defaults().

method_info()

std::string stir::FourierRebinning::method_info ( ) const

inlineoverridevirtual

This method returns the type of the algorithm for the rebinning.

Implements stir::ProjDataRebinning.

rebin()

Succeeded stir::FourierRebinning::rebin ( )

overridevirtual

This method creates a stack of 2D rebinned sinograms from the whole 3D data set (i.e. the ProjData data) and saves it.

Implements stir::ProjDataRebinning.

References _PI, stir::error(), stir::Array< num_dimensions, elemT >::find_max(), stir::Array< num_dimensions, elemT >::find_min(), fore_debug_level, stir::ProjDataInfoCylindrical::get_average_ring_difference(), stir::Scanner::get_effective_ring_radius(), stir::VectorWithOffset< T >::get_max_index(), stir::ProjDataInfoCylindrical::get_max_ring_difference(), stir::DataWithProjDataInfo::get_max_tangential_pos_num(), stir::DataWithProjDataInfo::get_max_view_num(), stir::VectorWithOffset< T >::get_min_index(), stir::DataWithProjDataInfo::get_min_tangential_pos_num(), stir::DataWithProjDataInfo::get_min_view_num(), stir::DataWithProjDataInfo::get_num_views(), stir::DataWithProjDataInfo::get_proj_data_info_sptr(), stir::Scanner::get_ring_spacing(), stir::Segment< elemT >::get_segment_num(), stir::SegmentBySinogram< elemT >::grow(), stir::info(), stir::inverse_fourier_for_real_data(), stir::ProjDataRebinning::max_segment_num_to_process, stir::ProjDataRebinning::output_filename_prefix, rebin(), stir::ProjDataInfoCylindrical::set_max_ring_difference(), stir::ProjDataInfoCylindrical::set_min_ring_difference(), stir::Timer::start(), stir::TimedObject::start_timers(), stir::TimedObject::stop_timers(), and stir::Array< num_dimensions, elemT >::sum().

Referenced by rebin().

post_processing()

bool stir::FourierRebinning::post_processing ( )

overrideprotectedvirtual

This will be called at the end of the parsing.

Returns

false if everything OK, true if not

Reimplemented from stir::ParsingObject.

References post_processing(), and stir::ProjDataRebinning::post_processing().

Referenced by post_processing().

initialise_keymap()

void stir::FourierRebinning::initialise_keymap ( )

overrideprotectedvirtual

Initialise all keywords.

Reimplemented from stir::ParsingObject.

References deltamin, fore_debug_level, initialise_keymap(), stir::ProjDataRebinning::initialise_keymap(), kc, kmin, and wmin.

Referenced by initialise_keymap().

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The documentation for this class was generated from the following files:

• /home/kris/devel/STIRdistrib/STIR/src/include/stir/recon_buildblock/FourierRebinning.h
• /home/kris/devel/STIRdistrib/STIR/src/recon_buildblock/FourierRebinning.cxx