X-Git-Url: http://git.kpe.io/?p=ctsim.git;a=blobdiff_plain;f=libctsim%2Fprojections.cpp;h=e5c79e7364f67a15a0a1ec5ce4b08f01ed0d2df7;hp=7c092f5990af43a9e267092a1f4a92042083ecc8;hb=728e9fcbe0b785e56e7dcd2bd305786c647050af;hpb=7cb74b55a21d0ab57a584ce3c910c280beb7a329

diff --git a/libctsim/projections.cpp b/libctsim/projections.cpp
index 7c092f5..e5c79e7 100644
--- a/libctsim/projections.cpp
+++ b/libctsim/projections.cpp
@@ -8,7 +8,7 @@
 **  This is part of the CTSim program
 **  Copyright (c) 1983-2001 Kevin Rosenberg
 **
-**  $Id: projections.cpp,v 1.52 2001/03/02 05:10:22 kevin Exp $
+**  $Id: projections.cpp,v 1.72 2001/03/29 21:25:49 kevin Exp $
 **
 **  This program is free software; you can redistribute it and/or modify
 **  it under the terms of the GNU General Public License (version 2) as
@@ -50,6 +50,7 @@ const char* const Projections::s_aszInterpTitle[] =
 const int Projections::s_iInterpCount = sizeof(s_aszInterpName) / sizeof(char*);
 
 
+
 /* NAME
 *    Projections		Constructor for projections matrix storage 
 *
@@ -150,12 +151,12 @@ Projections::initFromScanner (const Scanner& scanner)
   
   m_rotInc = scanner.rotInc();
   m_detInc = scanner.detInc();
+  m_detStart =  scanner.detStart();
   m_geometry = scanner.geometry();
   m_dFocalLength = scanner.focalLength();
   m_dSourceDetectorLength = scanner.sourceDetectorLength();
   m_dViewDiameter = scanner.viewDiameter();
   m_rotStart = 0;
-  m_detStart =  -(scanner.detLen() / 2);
   m_dFanBeamAngle = scanner.fanBeamAngle();
 }
 
@@ -687,29 +688,37 @@ Projections::convertPolar (ImageFile& rIF, int iInterpolationID)
 
   if (! v || nx == 0 || ny == 0)
     return false;
+
+  Projections* pProj = this;
+  if (m_geometry == Scanner::GEOMETRY_EQUIANGULAR || m_geometry == Scanner::GEOMETRY_EQUILINEAR)
+    pProj = interpolateToParallel();
   
   Array2d<double> adView (nx, ny);
   Array2d<double> adDet (nx, ny);
   double** ppdView = adView.getArray();
   double** ppdDet = adDet.getArray();
 
-  if (! calcArrayPolarCoordinates (nx, ny, ppdView, ppdDet)) 
-    return false;
-
-  std::complex<double>** ppcDetValue = new std::complex<double>* [m_nView];
+  std::complex<double>** ppcDetValue = new std::complex<double>* [pProj->m_nView];
   unsigned int iView;
-  for (iView = 0; iView < m_nView; iView++) {
-    ppcDetValue[iView] = new std::complex<double> [m_nDet];
-    for (unsigned int iDet = 0; iDet < m_nDet; iDet++)
-      ppcDetValue[iView][iDet] = std::complex<double>(getDetectorArray (iView).detValues()[iDet], 0);
+  for (iView = 0; iView < pProj->m_nView; iView++) {
+    ppcDetValue[iView] = new std::complex<double> [pProj->m_nDet];
+    DetectorValue* detval = pProj->getDetectorArray (iView).detValues();
+    for (unsigned int iDet = 0; iDet < pProj->m_nDet; iDet++)
+      ppcDetValue[iView][iDet] = std::complex<double>(detval[iDet], 0);
   }
 
-  interpolatePolar (v, vImag, nx, ny, ppcDetValue, ppdView, ppdDet, m_nView, m_nDet, iInterpolationID);
+  pProj->calcArrayPolarCoordinates (nx, ny, ppdView, ppdDet, pProj->m_nDet, 1., pProj->m_detInc);
+
+  pProj->interpolatePolar (v, vImag, nx, ny, ppcDetValue, ppdView, ppdDet, pProj->m_nView, pProj->m_nDet, 
+    pProj->m_nDet, iInterpolationID);
 
-  for (iView = 0; iView < m_nView; iView++)
+  for (iView = 0; iView < pProj->m_nView; iView++)
     delete [] ppcDetValue[iView];
   delete [] ppcDetValue;
 
+  if (m_geometry == Scanner::GEOMETRY_EQUIANGULAR || m_geometry == Scanner::GEOMETRY_EQUILINEAR)
+    delete pProj;
+
   return true;
 }
 
@@ -717,6 +726,10 @@ Projections::convertPolar (ImageFile& rIF, int iInterpolationID)
 bool 
 Projections::convertFFTPolar (ImageFile& rIF, int iInterpolationID, int iZeropad)
 {
+#ifndef HAVE_FFTW
+  rIF.arrayDataClear();
+  return false;
+#else
   unsigned int nx = rIF.nx();
   unsigned int ny = rIF.ny();
   ImageFileArray v = rIF.getArray();
@@ -727,68 +740,100 @@ Projections::convertFFTPolar (ImageFile& rIF, int iInterpolationID, int iZeropad
   if (! v || nx == 0 || ny == 0)
     return false;
   
-#ifndef HAVE_FFT
-  return false;
-#else
-  Array2d<double> adView (nx, ny);
-  Array2d<double> adDet (nx, ny);
-  double** ppdView = adView.getArray();
-  double** ppdDet = adDet.getArray();
+  if (m_geometry != Scanner::GEOMETRY_PARALLEL) {
+    sys_error (ERR_WARNING, "convertFFTPolar supports Parallel only");
+    return false;
+  }
+
+  int iInterpDet = nx;
+  int iNumInterpDetWithZeros = ProcessSignal::addZeropadFactor (iInterpDet, iZeropad);
+
+  double dZeropadRatio = static_cast<double>(iNumInterpDetWithZeros) / static_cast<double>(iInterpDet);
 
+  fftw_plan plan = fftw_create_plan (iNumInterpDetWithZeros, FFTW_FORWARD, FFTW_IN_PLACE | FFTW_ESTIMATE | FFTW_USE_WISDOM);
+
+  fftw_complex* pcIn = new fftw_complex [iNumInterpDetWithZeros];
   std::complex<double>** ppcDetValue = new std::complex<double>* [m_nView];
-  unsigned int iView;
-  double* pdDet = new double [m_nDet];
-  fftw_complex* pcIn = new fftw_complex [m_nDet];
-  fftw_plan plan = fftw_create_plan (m_nDet, FFTW_FORWARD, FFTW_IN_PLACE);
-
-  for (iView = 0; iView < m_nView; iView++) {
-    unsigned int iDet;
-    for (iDet = 0; iDet < m_nDet; iDet++) {
-      pcIn[iDet].re = getDetectorArray(iView).detValues()[iDet];
+  double dInterpScale = (m_nDet-1) / static_cast<double>(iInterpDet-1) / SQRT2;
+  
+  double dFFTScale = 1. / static_cast<double>(iInterpDet * iInterpDet);
+  int iMidPoint = iInterpDet / 2;
+  double dMidPoint = static_cast<double>(iInterpDet) / 2.;
+  int iZerosAdded = iNumInterpDetWithZeros - iInterpDet;
+  for (unsigned int iView = 0; iView < m_nView; iView++) {
+    DetectorValue* detval = getDetectorArray(iView).detValues();
+    LinearInterpolator<DetectorValue> projInterp (detval, m_nDet);
+    for (unsigned int iDet = 0; iDet < iInterpDet; iDet++) {
+      double dInterpPos = (m_nDet / 2.) + (iDet - dMidPoint) * dInterpScale;
+      pcIn[iDet].re = projInterp.interpolate (dInterpPos) * dInterpScale;
       pcIn[iDet].im = 0;
     }
+    Fourier::shuffleFourierToNaturalOrder (pcIn, iInterpDet);
+    if (iZerosAdded > 0) {
+      for (unsigned int iDet1 = iMidPoint; iDet1 < iInterpDet; iDet1++)
+        pcIn[iDet1+iZerosAdded] = pcIn[iDet1];
+      for (unsigned int iDet2 = iMidPoint; iDet2 < iMidPoint + iZerosAdded; iDet2++) 
+        pcIn[iDet2].re = pcIn[iDet2].im = 0;
+    }
+
     fftw_one (plan, pcIn, NULL);
-    ppcDetValue[iView] = new std::complex<double> [m_nDet];
-    for (iDet = 0; iDet < m_nDet; iDet++)
-      ppcDetValue[iView][iDet] = std::complex<double> (pcIn[iDet].re, pcIn[iDet].im); 
-    Fourier::shuffleFourierToNaturalOrder (ppcDetValue[iView], m_nDet);
+
+    ppcDetValue[iView] = new std::complex<double> [iNumInterpDetWithZeros];
+    for (unsigned int iD = 0; iD < iNumInterpDetWithZeros; iD++) {
+      ppcDetValue[iView][iD] = std::complex<double> (pcIn[iD].re * dFFTScale, pcIn[iD].im * dFFTScale); 
+    }
+
+    Fourier::shuffleFourierToNaturalOrder (ppcDetValue[iView], iNumInterpDetWithZeros);
   }
+  delete [] pcIn;
 
   fftw_destroy_plan (plan);  
-  delete [] pcIn;
   
-  bool bError = calcArrayPolarCoordinates (nx, ny, ppdView, ppdDet);
+  Array2d<double> adView (nx, ny);
+  Array2d<double> adDet (nx, ny);
+  double** ppdView = adView.getArray();
+  double** ppdDet = adDet.getArray();
+  calcArrayPolarCoordinates (nx, ny, ppdView, ppdDet, iNumInterpDetWithZeros, dZeropadRatio, 
+    m_detInc * dInterpScale);
 
-  if (! bError)
-    interpolatePolar (v, vImag, nx, ny, ppcDetValue, ppdView, ppdDet, m_nView, m_nDet, iInterpolationID);
+  interpolatePolar (v, vImag, nx, ny, ppcDetValue, ppdView, ppdDet, m_nView, m_nDet, iNumInterpDetWithZeros,
+    iInterpolationID);
 
-  for (iView = 0; iView < m_nView; iView++)
-    delete [] ppcDetValue[iView];
+  for (int i = 0; i < m_nView; i++)
+    delete [] ppcDetValue[i];
   delete [] ppcDetValue;
 
-  return bError;
+  return true;
 #endif
 }
 
 
-bool
-Projections::calcArrayPolarCoordinates (unsigned int nx, unsigned int ny, double** ppdView, double** ppdDet)
+void
+Projections::calcArrayPolarCoordinates (unsigned int nx, unsigned int ny, double** ppdView, double** ppdDet,
+                                        int iNumDetWithZeros, double dZeropadRatio, double dDetInc)
 {
-  double xMin = -phmLen() / 2;
-  double xMax = xMin + phmLen();
-  double yMin = -phmLen() / 2;
-  double yMax = yMin + phmLen();
-  
+//  double dLength = viewDiameter();
+  double dLength = phmLen();
+  double xMin = -dLength / 2;
+  double xMax = xMin + dLength;
+  double yMin = -dLength / 2;
+  double yMax = yMin + dLength;
+  double xCent = (xMin + xMax) / 2;
+  double yCent = (yMin + yMax) / 2;
+
+  xMin = (xMin - xCent) * dZeropadRatio + xCent;
+  xMax = (xMax - xCent) * dZeropadRatio + xCent;
+  yMin = (yMin - yCent) * dZeropadRatio + yCent;
+  yMax = (yMax - yCent) * dZeropadRatio + yCent;
+
   double xInc = (xMax - xMin) / nx;	// size of cells
   double yInc = (yMax - yMin) / ny;
-  
-  int iDetCenter = (m_nDet - 1) / 2;	// index refering to L=0 projection 
 
-  if (m_geometry != Scanner::GEOMETRY_PARALLEL) {
-    sys_error (ERR_WARNING, "convertPolar supports Parallel only");
-    return false;
-  }
-  
+  // +1 is correct for frequency data, ndet-1 is correct for projections
+  int iDetCenter = (iNumDetWithZeros - 1) / 2;	// index refering to L=0 projection 
+  if (isEven (iNumDetWithZeros))
+    iDetCenter = (iNumDetWithZeros + 1) / 2;	
+
   // Calculates polar coordinates (view#, det#) for each point on phantom grid
   double x = xMin + xInc / 2;	// Rectang coords of center of pixel 
   for (unsigned int ix = 0; ix < nx; x += xInc, ix++) {
@@ -797,168 +842,351 @@ Projections::calcArrayPolarCoordinates (unsigned int nx, unsigned int ny, double
       double r = ::sqrt (x * x + y * y);
       double phi = atan2 (y, x);
 
+      if (phi < 0)
+        phi += TWOPI;
       if (phi >= PI) {
         phi -= PI;
-      } else if (phi < 0) {
-        phi += PI;
-      } else
         r = -r;
+      }
       
       ppdView[ix][iy] = (phi - m_rotStart) / m_rotInc;
-      ppdDet[ix][iy] = (r / m_detInc) + iDetCenter;
+      ppdDet[ix][iy] = (r / dDetInc) + iDetCenter;
     }
   }
-
-  return true;
 }
 
 void
 Projections::interpolatePolar (ImageFileArray& v, ImageFileArray& vImag,
-     unsigned int nx, unsigned int ny, std::complex<double>** ppcDetValue,
-     double** ppdView, double** ppdDet, unsigned int nView, unsigned int nDet, int iInterpolationID)
+     unsigned int nx, unsigned int ny, std::complex<double>** ppcDetValue, double** ppdView, 
+     double** ppdDet, unsigned int nView, unsigned int nDet, unsigned int nDetWithZeros, int iInterpolationID)
 {
+  typedef std::complex<double> complexValue;
+
+  BilinearInterpolator<complexValue>* pBilinear;  
+  if (iInterpolationID == POLAR_INTERP_BILINEAR)
+    pBilinear = new BilinearInterpolator<complexValue> (ppcDetValue, nView, nDetWithZeros);
+
+  BicubicPolyInterpolator<complexValue>* pBicubic;  
+  if (iInterpolationID == POLAR_INTERP_BICUBIC)
+    pBicubic = new BicubicPolyInterpolator<complexValue> (ppcDetValue, nView, nDetWithZeros);
+
   for (unsigned int ix = 0; ix < ny; ix++) {
     for (unsigned int iy = 0; iy < ny; iy++) {
+
       if (iInterpolationID == POLAR_INTERP_NEAREST) {
-        int iView = nearest<int> (ppdView[ix][iy]);
-        int iDet = nearest<int> (ppdDet[ix][iy]);
+        unsigned int iView = nearest<int> (ppdView[ix][iy]);
+        unsigned int iDet = nearest<int> (ppdDet[ix][iy]);
         if (iView == nView) {
           iView = 0;
-       //   iDet = m_nDet - iDet;
+          iDet = m_nDet - iDet;
         }
-        if (iDet >= 0 && iDet < nDet && iView >= 0 && iView < nView) {
+        if (iDet >= 0 && iDet < nDetWithZeros && iView >= 0 && iView < nView) {
           v[ix][iy] = ppcDetValue[iView][iDet].real();
           if (vImag)
             vImag[ix][iy] = ppcDetValue[iView][iDet].imag();
-        } else {
-          sys_error (ERR_SEVERE, "Can't find projection data for ix=%d,iy=%d with radView=%f and radDet=%f", 
-            ix, iy, ppdView[ix][iy], ppdDet[ix][iy]);
+        } else
           v[ix][iy] = 0;
-        }
+
       } else if (iInterpolationID == POLAR_INTERP_BILINEAR) {
-        int iFloorView = static_cast<int>(ppdView[ix][iy]);
-        double dFracView = ppdView[ix][iy] - iFloorView;
-        int iFloorDet = static_cast<int>(ppdDet[ix][iy]);
-        double dFracDet = ppdDet[ix][iy] - iFloorDet;
-
-        if (iFloorDet >= 0 && iFloorView >= 0) { 
-          std::complex<double> v1 = ppcDetValue[iFloorView][iFloorDet];
-          std::complex<double> v2, v3, v4;
-          if (iFloorView < nView - 1)
-            v2 = ppcDetValue[iFloorView + 1][iFloorDet];
-          else 
-            v2 = ppcDetValue[0][iFloorDet];
-          if (iFloorDet < nDet - 1) 
-            v4 = ppcDetValue[iFloorView][iFloorDet+1];
-          else
-            v4 = v1;
-          if (iFloorView < nView - 1 && iFloorDet < nDet - 1)
-            v3 = ppcDetValue [iFloorView+1][iFloorDet+1];
-          else if (iFloorView < nView - 1)
-            v3 = v2;
-          else 
-            v3 = ppcDetValue[0][iFloorDet+1];
-          std::complex<double> vInterp = (1 - dFracView) * (1 - dFracDet) * v1 +
-            dFracView * (1 - dFracDet) * v2 + dFracView * dFracDet * v3 +
-            dFracDet * (1 - dFracView) * v4;
-          v[ix][iy] = vInterp.real();
-          if (vImag)
-            vImag[ix][iy] = vInterp.imag();
-        } else {
-          sys_error (ERR_SEVERE, "Can't find projection data for ix=%d,iy=%d with radView=%f and radDet=%f", 
-            ix, iy, ppdView[ix][iy], ppdDet[ix][iy]);
-          v[ix][iy] = 0;
-          if (vImag)
-            vImag[ix][iy] = 0;
-        }
+        std::complex<double> vInterp = pBilinear->interpolate (ppdView[ix][iy], ppdDet[ix][iy]);
+        v[ix][iy] = vInterp.real();
+        if (vImag)
+          vImag[ix][iy] = vInterp.imag();
       } else if (iInterpolationID == POLAR_INTERP_BICUBIC) {
-        v[ix][iy] =0;
-          if (vImag)
-            vImag[ix][iy] = 0;
+        std::complex<double> vInterp = pBicubic->interpolate (ppdView[ix][iy], ppdDet[ix][iy]);
+        v[ix][iy] = vInterp.real();
+        if (vImag)
+          vImag[ix][iy] = vInterp.imag();
       }
     }
   }
 }
 
-
 bool
 Projections::initFromSomatomAR_STAR (int iNViews, int iNDets, unsigned char* pData, unsigned long lDataLength)
 {
   init (iNViews, iNDets);
   m_geometry = Scanner::GEOMETRY_EQUIANGULAR;
-  m_dFanBeamAngle = iNDets * convertDegreesToRadians (3.06976 / 60);
-  m_dFocalLength = 51;
-  m_dSourceDetectorLength = 89;
+  m_dFocalLength = 510;
+  m_dSourceDetectorLength = 890;
   m_detInc = convertDegreesToRadians (3.06976 / 60);
-  m_detStart = -m_dFanBeamAngle / 2;
+  m_dFanBeamAngle = iNDets * m_detInc;
+  m_detStart = -(m_dFanBeamAngle / 2);
   m_rotInc = TWOPI / static_cast<double>(iNViews);
   m_rotStart = 0;
   m_dViewDiameter = sin (m_dFanBeamAngle / 2) * m_dFocalLength * 2;
 
-  if (iNDets != 1024)
-    return false;
-  bool bValid = (iNViews == 750 && lDataLength == 1560000L) || (iNViews == 950 && lDataLength == 1976000L) || (iNViews == 1500 && lDataLength == 3120000);
-  if (! bValid)
+  if (! ((iNViews == 750 && lDataLength == 1560000L) || (iNViews == 950 && lDataLength == 1976000L) 
+                || (iNViews == 1500 && lDataLength == 3120000)))
     return false;
 
+  double dCenter = (iNDets - 1.) / 2.; // change from (Nm+1)/2 because of 0 vs. 1 indexing
+  double* pdCosScale = new double [iNDets];
+  for (int i = 0; i < iNDets; i++)
+    pdCosScale[i] = 1. / cos ((i - dCenter) * m_detInc);
+
   long lDataPos = 0;
   for (int iv = 0; iv < iNViews; iv++) {
-    long* pLong = reinterpret_cast<long*>(pData + lDataPos+0);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pLong);
-#endif
-    long lProjNumber = *pLong;
-
-    pLong = reinterpret_cast<long*>(pData + lDataPos+20);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pLong);
-#endif
-    long lEscale = *pLong;
+    unsigned char* pArgBase = pData + lDataPos;
+    unsigned char* p = pArgBase+0; SwapBytes4IfLittleEndian (p);
+    long lProjNumber = *reinterpret_cast<long*>(p);
 
-    pLong = reinterpret_cast<long*>(pData + lDataPos+28);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pLong);
-#endif
-    long lTime = *pLong;
+    p = pArgBase+20;  SwapBytes4IfLittleEndian (p);
+    long lEscale = *reinterpret_cast<long*>(p);
 
-    float* pFloat = reinterpret_cast<float*>(pData + lDataPos+4);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pFloat);
-#endif
-    double dAlpha = *pFloat;
+    p = pArgBase+28;  SwapBytes4IfLittleEndian (p);
+    long lTime = *reinterpret_cast<long*>(p);
 
-    pFloat = reinterpret_cast<float*>(pData + lDataPos+12);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pFloat);
-#endif
-    double dAlign = *pFloat;
+    p = pArgBase + 4; SwapBytes4IfLittleEndian (p);
+    double dAlpha = *reinterpret_cast<float*>(p) + HALFPI;
 
-    pFloat = reinterpret_cast<float*>(pData + lDataPos+16);
-#ifndef WORDS_BIGENDIAN
-    SwapBytes4 (pFloat);
-#endif
-    double dMaxValue = *pFloat;
+    p = pArgBase+12; SwapBytes4IfLittleEndian (p);
+    double dAlign = *reinterpret_cast<float*>(p);
 
-    lDataPos += 32;
-    double dEScale =  pow (2.0, -lEscale);
-    double dBetaInc = convertDegreesToRadians (3.06976 / 60);
-    int iCenter = (iNDets + 1) / 2;
+    p = pArgBase + 16; SwapBytes4IfLittleEndian (p);
+    double dMaxValue = *reinterpret_cast<float*>(p);
 
-    DetectorArray& detArray = getDetectorArray( iv );
+    DetectorArray& detArray = getDetectorArray (iv);
     detArray.setViewAngle (dAlpha);
     DetectorValue* detval = detArray.detValues();
 
-    double dTempScale = 2294.4871 * dEScale;
+    double dViewScale = 1. / (2294.4871 * ::pow (2.0, -lEscale));
+    lDataPos += 32;
     for (int id = 0; id < iNDets; id++) {
-      int iV = pData[lDataPos+1] + 256 * pData[lDataPos];
-      if (iV > 32767)
+      int iV = pData[lDataPos+1] + (pData[lDataPos] << 8);
+      if (iV > 32767)   // two's complement signed conversion
         iV = iV - 65536;
-      double dCosScale = cos ((id + 1 - iCenter) * dBetaInc);
-      detval[id] = iV / (dTempScale * dCosScale);
+      detval[id] = iV * dViewScale * pdCosScale[id];
       lDataPos += 2;
     }
+#if 1
+    for (int k = iNDets - 2; k >= 0; k--)
+      detval[k+1] = detval[k];
+    detval[0] = 0;
+#endif
   }
 
+  delete pdCosScale;
   return true;
 }
 
+Projections*
+Projections::interpolateToParallel () const
+{
+  if (m_geometry == Scanner::GEOMETRY_PARALLEL)
+    return const_cast<Projections*>(this);
+
+  int nDet = m_nDet;
+  int nView = m_nView;
+  Projections* pProjNew = new Projections (nView, nDet);
+  pProjNew->m_geometry = Scanner::GEOMETRY_PARALLEL;
+  pProjNew->m_dFocalLength = m_dFocalLength;
+  pProjNew->m_dSourceDetectorLength = m_dSourceDetectorLength;
+  pProjNew->m_dViewDiameter = m_dViewDiameter;
+  pProjNew->m_dFanBeamAngle = m_dFanBeamAngle;
+  pProjNew->m_calcTime  = 0;
+  pProjNew->m_remark = m_remark;
+  pProjNew->m_remark += "; Interpolate to Parallel";
+  pProjNew->m_label.setLabelType (Array2dFileLabel::L_HISTORY);
+  pProjNew->m_label.setLabelString (pProjNew->m_remark);
+  pProjNew->m_label.setCalcTime (pProjNew->m_calcTime);
+  pProjNew->m_label.setDateTime (pProjNew->m_year, pProjNew->m_month, pProjNew->m_day, pProjNew->m_hour, pProjNew->m_minute, pProjNew->m_second);
+
+  pProjNew->m_rotStart = 0;
+#ifdef CONVERT_PARALLEL_PI
+  pProjNew->m_rotInc = PI / nView;;
+#else
+  pProjNew->m_rotInc = TWOPI / nView;
+#endif
+  pProjNew->m_detStart = -m_dViewDiameter / 2;
+  pProjNew->m_detInc = m_dViewDiameter / nDet;
+  if (isEven (nDet)) // even
+    pProjNew->m_detInc = m_dViewDiameter / (nDet - 1);
+
+  ParallelRaysums parallel (this, ParallelRaysums::THETA_RANGE_NORMALIZE_TO_TWOPI);
+
+  double* pdThetaValuesForT = new double [pProjNew->nView()];
+  double* pdRaysumsForT = new double [pProjNew->nView()];
+
+  // interpolate to evenly spaced theta (views)
+  double dDetPos = pProjNew->m_detStart;
+  for (int iD = 0; iD < pProjNew->nDet(); iD++, dDetPos += pProjNew->m_detInc) {
+      parallel.getThetaAndRaysumsForT (iD, pdThetaValuesForT, pdRaysumsForT);
+
+    double dViewAngle = m_rotStart;
+    int iLastFloor = -1;
+    for (int iV = 0; iV < pProjNew->nView(); iV++, dViewAngle += pProjNew->m_rotInc) {
+      DetectorValue* detValues = pProjNew->getDetectorArray (iV).detValues();
+      LinearInterpolator<double> interp (pdThetaValuesForT, pdRaysumsForT, pProjNew->nView(), false);
+      detValues[iD] = interp.interpolate (dViewAngle, &iLastFloor);
+    }
+  }
+  delete pdThetaValuesForT;
+  delete pdRaysumsForT;
+
+  // interpolate to evenly space t (detectors)
+  double* pdOriginalDetPositions = new double [pProjNew->nDet()];
+  parallel.getDetPositions (pdOriginalDetPositions);
+
+  double* pdDetValueCopy = new double [pProjNew->nDet()];
+  double dViewAngle = m_rotStart;
+  for (int iV = 0; iV < pProjNew->nView(); iV++, dViewAngle += pProjNew->m_rotInc) {
+    DetectorArray& detArray = pProjNew->getDetectorArray (iV);
+    DetectorValue* detValues = detArray.detValues();
+    detArray.setViewAngle (dViewAngle);
+
+    for (int i = 0; i < pProjNew->nDet(); i++)
+      pdDetValueCopy[i] =   detValues[i];
+
+    double dDetPos = pProjNew->m_detStart;
+    int iLastFloor = -1;
+    LinearInterpolator<double> interp (pdOriginalDetPositions, pdDetValueCopy, pProjNew->nDet(), false);
+    for (int iD = 0; iD < pProjNew->nDet(); iD++, dDetPos += pProjNew->m_detInc)
+      detValues[iD] = interp.interpolate (dDetPos, &iLastFloor);
+  }
+  delete pdDetValueCopy;
+  delete pdOriginalDetPositions;
+
+  return pProjNew;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+//
+// Class ParallelRaysums
+//
+// Used for converting divergent beam raysums into Parallel raysums
+//
+///////////////////////////////////////////////////////////////////////////////
+
+ParallelRaysums::ParallelRaysums (const Projections* pProjections, int iThetaRange)
+: m_iNumCoordinates(0), m_iNumView(pProjections->nView()), m_iNumDet(pProjections->nDet()),
+  m_iThetaRange (iThetaRange), m_pCoordinates(NULL)
+{
+  int iGeometry = pProjections->geometry();
+  double dDetInc = pProjections->detInc();
+  double dDetStart = pProjections->detStart();
+  double dFocalLength = pProjections->focalLength();
+
+  m_iNumCoordinates =  m_iNumView * m_iNumDet;
+  m_pCoordinates = new ParallelRaysumCoordinate [m_iNumCoordinates];
+  m_vecpCoordinates.reserve (m_iNumCoordinates);
+  for (int i = 0; i < m_iNumCoordinates; i++)
+    m_vecpCoordinates[i] = m_pCoordinates + i;
+
+  int iCoordinate = 0;
+  for (int iV = 0; iV < m_iNumView; iV++) {
+    double dViewAngle = pProjections->getDetectorArray(iV).viewAngle();
+    const DetectorValue* detValues = pProjections->getDetectorArray(iV).detValues();
+
+    double dDetPos = dDetStart;
+    for (int iD = 0; iD < m_iNumDet; iD++) {
+      ParallelRaysumCoordinate* pC = m_vecpCoordinates[iCoordinate++];
+
+      if (iGeometry == Scanner::GEOMETRY_PARALLEL) {
+        pC->m_dTheta = dViewAngle;
+        pC->m_dT = dDetPos;
+      } else if (iGeometry == Scanner::GEOMETRY_EQUILINEAR) {
+        double dFanAngle = atan (dDetPos / pProjections->sourceDetectorLength());
+        pC->m_dTheta = dViewAngle + dFanAngle;
+        pC->m_dT = dFocalLength * sin(dFanAngle);        
+
+      } else if (iGeometry == Scanner::GEOMETRY_EQUIANGULAR) {
+        // fan angle is same as dDetPos
+        pC->m_dTheta = dViewAngle + dDetPos;
+        pC->m_dT = dFocalLength * sin (dDetPos);        
+      }
+      if (m_iThetaRange != THETA_RANGE_UNCONSTRAINED) {
+        pC->m_dTheta = normalizeAngle (pC->m_dTheta);
+        if (m_iThetaRange == THETA_RANGE_FOLD_TO_PI && pC->m_dTheta >= PI) {
+          pC->m_dTheta -= PI;
+          pC->m_dT = -pC->m_dT;
+        }
+      }
+      pC->m_dRaysum = detValues[iD];
+      dDetPos += dDetInc;
+    }
+  }
+}
+
+ParallelRaysums::~ParallelRaysums()
+{
+  delete m_pCoordinates;
+}
+
+ParallelRaysums::CoordinateContainer&
+ParallelRaysums::getSortedByTheta()
+{
+  if (m_vecpSortedByTheta.size() == 0) {
+    m_vecpSortedByTheta.resize (m_iNumCoordinates);
+    for (int i = 0; i < m_iNumCoordinates; i++)
+      m_vecpSortedByTheta[i] = m_vecpCoordinates[i];
+    std::sort (m_vecpSortedByTheta.begin(), m_vecpSortedByTheta.end(), ParallelRaysumCoordinate::compareByTheta);
+  }
+
+  return m_vecpSortedByTheta;
+}
+
+ParallelRaysums::CoordinateContainer&
+ParallelRaysums::getSortedByT()
+{
+  if (m_vecpSortedByT.size() == 0) {
+    m_vecpSortedByT.resize (m_iNumCoordinates);
+    for (int i = 0; i < m_iNumCoordinates; i++)
+      m_vecpSortedByT[i] = m_vecpCoordinates[i];
+    std::sort (m_vecpSortedByT.begin(), m_vecpSortedByT.end(), ParallelRaysumCoordinate::compareByT);
+  }
+
+  return m_vecpSortedByT;
+}
+
+
+void
+ParallelRaysums::getLimits (double* dMinT, double* dMaxT, double* dMinTheta, double* dMaxTheta) const
+{
+  if (m_iNumCoordinates <= 0)
+    return;
+
+  *dMinT = *dMaxT = m_vecpCoordinates[0]->m_dT;
+  *dMinTheta = *dMaxTheta = m_vecpCoordinates[0]->m_dTheta;
+
+  for (int i = 0; i < m_iNumCoordinates; i++) {
+    double dT = m_vecpCoordinates[i]->m_dT;
+    double dTheta = m_vecpCoordinates[i]->m_dTheta;
+
+    if (dT < *dMinT)
+      *dMinT = dT;
+    else if (dT > *dMaxT)
+      *dMaxT = dT;
+
+    if (dTheta < *dMinTheta)
+      *dMinTheta = dTheta;
+    else if (dTheta > *dMaxTheta)
+      *dMaxTheta = dTheta;
+  }
+}
+
+void
+ParallelRaysums::getThetaAndRaysumsForT (int iTheta, double* pTheta, double* pRaysum)
+{
+  const CoordinateContainer& coordsT = getSortedByT();
+
+  int iBase = iTheta * m_iNumView;
+  for (int i = 0; i < m_iNumView; i++) {
+    int iPos = iBase + i;
+    pTheta[i] = coordsT[iPos]->m_dTheta;
+    pRaysum[i] = coordsT[iPos]->m_dRaysum;
+  }
+}
+
+void
+ParallelRaysums::getDetPositions (double* pdDetPos)
+{
+  const CoordinateContainer& coordsT = getSortedByT();
+
+  int iPos = 0;
+  for (int i = 0; i < m_iNumDet; i++) {
+    pdDetPos[i] = coordsT[iPos]->m_dT;
+    iPos += m_iNumView;
+  }
+}