FFTResampleProcessor resamples an image by clipping the Fourier Transform This is the same as multipyling the FT by a box window, in real space this is a convolution that will induce rippling. More...

#include <processor.h>

Inheritance diagram for EMAN::FFTResampleProcessor:

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Collaboration diagram for EMAN::FFTResampleProcessor:

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Public Member Functions
virtual EMData *	process (const EMData *const image)
	To proccess an image out-of-place. More...

virtual void	process_inplace (EMData *image)
	To process an image in-place. More...

string	get_desc () const
	Get the descrition of this specific processor. More...

string	get_name () const
	Get the processor's name. More...

TypeDict	get_param_types () const
	Get processor parameter information in a dictionary. More...

Public Member Functions inherited from EMAN::Processor
virtual	~Processor ()

virtual void	process_list_inplace (vector< EMData * > &images)
	To process multiple images using the same algorithm. More...

virtual Dict	get_params () const
	Get the processor parameters in a key/value dictionary. More...

virtual void	set_params (const Dict &new_params)
	Set the processor parameters using a key/value dictionary. More...

Static Public Member Functions
static Processor *	NEW ()

Static Public Member Functions inherited from EMAN::Processor
static string	get_group_desc ()
	Get the description of this group of processors. More...

static void	EMFourierFilterInPlace (EMData *fimage, Dict params)
	Compute a Fourier-filter processed image in place. More...

static EMData *	EMFourierFilter (EMData *fimage, Dict params)
	Compute a Fourier-processor processed image without altering the original image. More...

Static Public Attributes
static const string	NAME = "math.fft.resample"

Private Member Functions
void	fft_resample (EMData to, const EMData const from, const float &sample_rate)
	An internal function that encapsulates a routine common to both process and process inplace. More...

Additional Inherited Members
Public Types inherited from EMAN::Processor
enum	fourier_filter_types { TOP_HAT_LOW_PASS , TOP_HAT_HIGH_PASS , TOP_HAT_BAND_PASS , TOP_HOMOMORPHIC , GAUSS_LOW_PASS , GAUSS_HIGH_PASS , GAUSS_BAND_PASS , GAUSS_INVERSE , GAUSS_HOMOMORPHIC , BUTTERWORTH_LOW_PASS , BUTTERWORTH_HIGH_PASS , BUTTERWORTH_HOMOMORPHIC , KAISER_I0 , KAISER_SINH , KAISER_I0_INVERSE , KAISER_SINH_INVERSE , SHIFT , TANH_LOW_PASS , TANH_HIGH_PASS , TANH_HOMOMORPHIC , TANH_BAND_PASS , RADIAL_TABLE , CTF_ }
	Fourier filter Processor type enum. More...

Protected Attributes inherited from EMAN::Processor
Dict	params

Detailed Description

FFTResampleProcessor resamples an image by clipping the Fourier Transform This is the same as multipyling the FT by a box window, in real space this is a convolution that will induce rippling.

Hence it should probably be combined with a damping function near the edge Works for even/odd, 1D, 2D and 3D images (completely robust, tested)

Author: David Woolford (fixed by Pawel Penczek, 2017)

Date: June 2009

Parameters

n	sampe_rate

Definition at line 5130 of file processor.h.

Member Function Documentation

◆ fft_resample()

void FFTResampleProcessor::fft_resample	(	EMData *	to,
		const EMData *const	from,
		const float &	sample_rate
	)

private

An internal function that encapsulates a routine common to both process and process inplace.

Parameters

to	the smaller image that will store the shrunken values
from	the larger image that will be used to calculate the shrunken values
shrinkfactor	the shrink amount

Definition at line 3074 of file processor.cpp.

                                                                                                      {
        int nx = from->get_xsize();
        int ny = from->get_ysize();
        int nz = from->get_zsize();
 
        int new_nx = static_cast<int>( static_cast<float> (nx) / sample_rate);
        int new_ny = static_cast<int>( static_cast<float> (ny) / sample_rate);
        int new_nz = static_cast<int>( static_cast<float> (nz) / sample_rate);
 
        if (new_nx == 0) throw UnexpectedBehaviorException("The resample rate causes the pixel dimensions in the x direction to go to zero");
        if (new_ny == 0) new_ny = 1;
        if (new_nz == 0) new_nz = 1;
 
        int ndim = from->get_ndim();
        if ( ndim < 3 ) {
                new_nz = 1;
        }
        if ( ndim < 2 ) {
                new_ny = 1;
        }
 
        int fft_x_correction = 1;
        if (new_nx % 2 == 0) fft_x_correction = 2;
 
        int fft_y_correction = 0;
        if (ny != 1 && new_ny % 2 == 0 && ny % 2 == 1) fft_y_correction = 1;
        else if (ny != 1 && new_ny % 2 == 1 && ny % 2 == 0) fft_y_correction = -1;
 
        int fft_z_correction = 0;
        if (nz != 1 && new_nz % 2 == 0 && nz % 2 == 1) fft_z_correction = 1;
        else if (nz != 1 && new_nz % 2 == 1 && nz % 2 == 0) fft_z_correction = -1;
 
        if ( ! to->is_complex()) to->do_fft_inplace();
 
        if (ndim != 1) to->process_inplace("xform.fourierorigin.tocenter");
 
        Region clip(0,(ny-new_ny)/2-fft_y_correction,(nz-new_nz)/2-fft_z_correction,new_nx+fft_x_correction,new_ny,new_nz);
        to->clip_inplace(clip);
 
        if (fft_x_correction == 1) to->set_fftodd(true);
        else to->set_fftodd(false);
 
        if (ndim != 1) to->process_inplace("xform.fourierorigin.tocorner");
 
        to->do_ift_inplace();
        to->depad_corner();
 
}

References EMAN::EMData::clip_inplace(), and UnexpectedBehaviorException.

◆ get_desc()

string EMAN::FFTResampleProcessor::get_desc ( ) const

inlinevirtual

Get the descrition of this specific processor.

This function must be overwritten by a subclass.

Returns: The description of this processor.

Implements EMAN::Processor.

Definition at line 5137 of file processor.h.

                        {
                                return "Robust resampling of an image by clipping its Fourier transform.";
                        }

◆ get_name()

string EMAN::FFTResampleProcessor::get_name ( ) const

inlinevirtual

Get the processor's name.

Each processor is identified by a unique name.

Returns: The processor's name.

Implements EMAN::Processor.

Definition at line 5142 of file processor.h.

                        {
                                return NAME;
                        }

References NAME.

◆ get_param_types()

TypeDict EMAN::FFTResampleProcessor::get_param_types ( ) const

inlinevirtual

Get processor parameter information in a dictionary.

Each parameter has one record in the dictionary. Each record contains its name, data-type, and description.

Returns: A dictionary containing the parameter info.

Reimplemented from EMAN::Processor.

Definition at line 5151 of file processor.h.

                        {
                                TypeDict d;
                                d.put("n", EMObject::FLOAT, "The sample rate. Less than one enlarges the image, greater than one shrinks it.");
                                return d;
                        }

References EMAN::EMObject::FLOAT, and EMAN::TypeDict::put().

◆ NEW()

static Processor * EMAN::FFTResampleProcessor::NEW ( )

inlinestatic

Definition at line 5146 of file processor.h.

                        {
                                return new FFTResampleProcessor();
                        }

◆ process()

EMData * FFTResampleProcessor::process ( const EMData *const image )

virtual

To proccess an image out-of-place.

For those processors which can only be processed out-of-place, override this function to give the right behavior.

Parameters

image The image will be copied, actual process happen on copy of image.

Returns: the image processing result, may or may not be the same size of the input image

Reimplemented from EMAN::Processor.

Definition at line 2989 of file processor.cpp.

{
        if (image->is_complex()) throw ImageFormatException("FFTResampleProcessor does not support complex images.");
 
        float sample_rate = params.set_default("n",0.0f);
        if (sample_rate <= 0.0F  )      {
                throw InvalidValueException(sample_rate,        "downsampling must be >0 ");
        }
 
        int nx=image->get_xsize();
        int ny=image->get_ysize();
        int nz=image->get_zsize();
 
        int nnx=(int)floor(nx/sample_rate+0.5f);
        int nny=(ny==1?1:(int)floor(ny/sample_rate+0.5f));
        int nnz=(nz==1?1:(int)floor(nz/sample_rate+0.5f));
 
        if (nnx==nx && nny==ny && nnz==nz) return image->copy();
 
        EMData *result;
        //downsample
        if (nnx<nx||nny<ny||nnz<nz) {
                // the type casting here is because FourTruncate was not defined to be const (but it is)
                result=((EMData *)image)->FourTruncate(nnx, nny, nnz, 1, 0);    // nnx,nny,nnz,returnreal,normalize
        } //upscale
        else {
                // the type casting here is because FourTruncate was not defined to be const (but it is)
                result=((EMData *)image)->FourInterpol(nnx, nny, nnz, 1, 0);    // nnx,nny,nnz,returnreal,normalize
        }
        result->scale_pixel((float)nx/(float)nnx);
        result->update();
        return result;
        
 
//      EMData* result;
//      if (image->is_complex()) result = image->copy();
//      else result = image->do_fft();
//      fft_resample(result,image,sample_rate);
        // The image may have been padded - we should shift it so that the phase origin is where FFTW expects it
//      result->update();
//      result->scale_pixel(sample_rate);
//      return result;
}

References ImageFormatException, InvalidValueException, EMAN::Processor::params, and EMAN::Dict::set_default().

◆ process_inplace()

void FFTResampleProcessor::process_inplace ( EMData * image )

virtual

To process an image in-place.

For those processors which can only be processed out-of-place, override this function to just print out some error message to remind user call the out-of-place version.

Parameters

image The image to be processed.

Implements EMAN::Processor.

Definition at line 3033 of file processor.cpp.

{
        float sample_rate = params.set_default("n",0.0f);
        if (sample_rate <= 0.0F  )      {
                throw InvalidValueException(sample_rate,        "sample rate (n) must be >0 ");
        }
        //if (image->is_complex()) throw ImageFormatException("Error, the fft resampling processor does not work on complex images");
 
        int nx=image->get_xsize();
        int ny=image->get_ysize();
        int nz=image->get_zsize();
 
        int nnx=(int)floor(nx/sample_rate+0.5f);
        int nny=(ny==1?1:(int)floor(ny/sample_rate+0.5f));
        int nnz=(nz==1?1:(int)floor(nz/sample_rate+0.5f));
 
        if (nnx==nx && nny==ny && nnz==nz) return;
 
        EMData *result;
        //downsample
        if (nnx<nx||nny<ny||nnz<nz) {
                // the type casting here is because FourTruncate was not defined to be const (but it is)
                result=((EMData *)image)->FourTruncate(nnx, nny, nnz, 1, 0);    // nnx,nny,nnz,returnreal,normalize
        } //upscale
        else {
                // the type casting here is because FourTruncate was not defined to be const (but it is)
                result=((EMData *)image)->FourInterpol(nnx, nny, nnz, 1, 0);    // nnx,nny,nnz,returnreal,normalize
        }
 
        image->set_size(nnx,nny,nnz);
        memcpy(image->get_data(),result->get_data(),nnx*nny*nnz*sizeof(float));
        image->scale_pixel((float)nx/(float)nnx);
        image->update();
        delete result;
 
        //fft_resample(image,image,sample_rate);
 
        //image->scale_pixel(sample_rate);
 
}

References InvalidValueException, EMAN::Processor::params, and EMAN::Dict::set_default().

Member Data Documentation

◆ NAME

const string FFTResampleProcessor::NAME = "math.fft.resample"

static

Definition at line 5158 of file processor.h.

Referenced by get_name().

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

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ fft_resample()

◆ get_desc()

◆ get_name()

◆ get_param_types()

◆ NEW()

◆ process()

◆ process_inplace()

Member Data Documentation

◆ NAME