X-Git-Url: http://git.kpe.io/?p=ctsim.git;a=blobdiff_plain;f=libctsim%2Fbackprojectors.cpp;h=0bcd4077cd527281d11769b4084c3d29e07cce1d;hp=71aa8d4824722d2940d874b0b87666007121954f;hb=a05f3cb550877e94aa118cc04b361c0c8fdb3dc3;hpb=6bfb747f8163381d94a02c03a0351e9ca6815d22 diff --git a/libctsim/backprojectors.cpp b/libctsim/backprojectors.cpp index 71aa8d4..0bcd407 100644 --- a/libctsim/backprojectors.cpp +++ b/libctsim/backprojectors.cpp @@ -8,7 +8,7 @@ ** This is part of the CTSim program ** Copyright (C) 1983-2000 Kevin Rosenberg ** -** $Id: backprojectors.cpp,v 1.12 2000/08/25 15:59:13 kevin Exp $ +** $Id: backprojectors.cpp,v 1.13 2000/08/31 08:38:58 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 @@ -148,22 +148,27 @@ Backprojector::initBackprojector (const Projections& proj, ImageFile& im, const return false; } - if (m_idBackproject == BPROJ_TRIG) - m_pBackprojectImplem = static_cast(new BackprojectTrig (proj, im, m_idInterpolation, interpFactor)); - else if (m_idBackproject == BPROJ_TABLE) - m_pBackprojectImplem = static_cast(new BackprojectTable (proj, im, m_idInterpolation, interpFactor)); - else if (m_idBackproject == BPROJ_DIFF) - m_pBackprojectImplem = static_cast(new BackprojectDiff (proj, im, m_idInterpolation, interpFactor)); - else if (m_idBackproject == BPROJ_DIFF2) - m_pBackprojectImplem = static_cast(new BackprojectDiff2 (proj, im, m_idInterpolation, interpFactor)); - else if (m_idBackproject == BPROJ_IDIFF2) - m_pBackprojectImplem = static_cast(new BackprojectIntDiff2 (proj, im, m_idInterpolation, interpFactor)); - else if (m_idBackproject == BPROJ_IDIFF3) - m_pBackprojectImplem = static_cast(new BackprojectIntDiff3 (proj, im, m_idInterpolation, interpFactor)); - else { - m_fail = true; - m_failMessage = "Unable to select a backprojection method [Backprojector::initBackprojector]"; - return false; + if (proj.geometry() == Scanner::GEOMETRY_EQUILINEAR) + m_pBackprojectImplem = static_cast(new BackprojectEquilinear(proj, im, m_idInterpolation, interpFactor)); + else if (proj.geometry() == Scanner::GEOMETRY_EQUIANGULAR) + m_pBackprojectImplem = static_cast(new BackprojectEquiangular(proj, im, m_idInterpolation, interpFactor)); + else if (proj.geometry() == Scanner::GEOMETRY_PARALLEL) { + if (m_idBackproject == BPROJ_TRIG) + m_pBackprojectImplem = static_cast(new BackprojectTrig (proj, im, m_idInterpolation, interpFactor)); + else if (m_idBackproject == BPROJ_TABLE) + m_pBackprojectImplem = static_cast(new BackprojectTable (proj, im, m_idInterpolation, interpFactor)); + else if (m_idBackproject == BPROJ_DIFF) + m_pBackprojectImplem = static_cast(new BackprojectDiff (proj, im, m_idInterpolation, interpFactor)); + else if (m_idBackproject == BPROJ_DIFF2) + m_pBackprojectImplem = static_cast(new BackprojectDiff2 (proj, im, m_idInterpolation, interpFactor)); + else if (m_idBackproject == BPROJ_IDIFF2) + m_pBackprojectImplem = static_cast(new BackprojectIntDiff2 (proj, im, m_idInterpolation, interpFactor)); + else if (m_idBackproject == BPROJ_IDIFF3) + m_pBackprojectImplem = static_cast(new BackprojectIntDiff3 (proj, im, m_idInterpolation, interpFactor)); + } else { + m_fail = true; + m_failMessage = "Unable to select a backprojection method [Backprojector::initBackprojector]"; + return false; } return true; @@ -256,7 +261,7 @@ Backproject::Backproject (const Projections& proj, ImageFile& im, const int inte { detInc = proj.detInc(); nDet = proj.nDet(); - iDetCenter = (nDet - 1) / 2; // index refering to L=0 projection + iDetCenter = nDet / 2; // index refering to L=0 projection rotInc = proj.rotInc(); v = im.getArray(); @@ -271,6 +276,8 @@ Backproject::Backproject (const Projections& proj, ImageFile& im, const int inte xInc = (xMax - xMin) / nx; // size of cells yInc = (yMax - yMin) / ny; + + m_dFocalLength = proj.focalLength(); } Backproject::~Backproject () @@ -312,12 +319,12 @@ void Backproject::errorIndexOutsideDetector (int ix, int iy, double theta, doubl void BackprojectTrig::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = HALFPI + view_angle; // Add PI/2 to get perpendicular angle to detector - int ix, iy; - double x, y; // Rectang coords of center of pixel + double theta = view_angle; - for (x = xMin + xInc / 2, ix = 0; ix < nx; x += xInc, ix++) - for (y = yMin + yInc / 2, iy = 0; iy < ny; y += yInc, iy++) { + double x = xMin + xInc / 2; // Rectang coords of center of pixel + for (int ix = 0; ix < nx; x += xInc, ix++) { + double y = yMin + yInc / 2; + for (int iy = 0; iy < ny; y += yInc, iy++) { double r = sqrt (x * x + y * y); // distance of cell from center double phi = atan2 (y, x); // angle of cell from center double L = r * cos (theta - phi); // position on detector @@ -340,6 +347,7 @@ BackprojectTrig::BackprojectView (const double* const filteredProj, const double v[ix][iy] += rotInc * ((1-frac) * filteredProj[iDetPos] + frac * filteredProj[iDetPos+1]); } } + } } @@ -374,7 +382,7 @@ BackprojectTable::~BackprojectTable () void BackprojectTable::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = HALFPI + view_angle; // add half PI to view angle to get perpendicular theta angle + double theta = view_angle; for (int ix = 0; ix < nx; ix++) { ImageFileColumn pImCol = v[ix]; @@ -431,9 +439,9 @@ BackprojectDiff::~BackprojectDiff() void BackprojectDiff::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = - view_angle; // add half PI to view angle to get perpendicular theta angle - double det_dx = xInc * sin (theta); - double det_dy = yInc * cos (theta); + double theta = view_angle; // add half PI to view angle to get perpendicular theta angle + double det_dx = xInc * cos (theta); + double det_dy = yInc * sin (theta); double lColStart = start_r * cos (theta - start_phi); // calculate L for first point in image for (int ix = 0; ix < nx; ix++, lColStart += det_dx) { @@ -475,11 +483,11 @@ BackprojectDiff::BackprojectView (const double* const filteredProj, const double void BackprojectDiff2::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = - view_angle; // add half PI to view angle to get perpendicular theta angle + double theta = view_angle; // Distance betw. detectors for an angle given in units of detectors - double det_dx = xInc * sin (theta) / detInc; - double det_dy = yInc * cos (theta) / detInc; + double det_dx = xInc * cos (theta) / detInc; + double det_dy = yInc * sin (theta) / detInc; // calculate detPosition for first point in image (ix=0, iy=0) double detPosColStart = start_r * cos (theta - start_phi) / detInc; @@ -524,14 +532,14 @@ BackprojectDiff2::BackprojectView (const double* const filteredProj, const doubl void BackprojectIntDiff2::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = - view_angle; // add half PI to view angle to get perpendicular theta angle + double theta = view_angle; static const kint32 scale = 1 << 16; static const double dScale = scale; static const kint32 halfScale = scale / 2; - const kint32 det_dx = nearest (xInc * sin (theta) / detInc * scale); - const kint32 det_dy = nearest (yInc * cos (theta) / detInc * scale); + const kint32 det_dx = nearest (xInc * cos (theta) / detInc * scale); + const kint32 det_dy = nearest (yInc * sin (theta) / detInc * scale); // calculate L for first point in image (0, 0) kint32 detPosColStart = nearest (start_r * cos (theta - start_phi) / detInc * scale); @@ -576,15 +584,15 @@ BackprojectIntDiff2::BackprojectView (const double* const filteredProj, const do void BackprojectIntDiff3::BackprojectView (const double* const filteredProj, const double view_angle) { - double theta = - view_angle; // add half PI to view angle to get perpendicular theta angle + double theta = view_angle; // add half PI to view angle to get perpendicular theta angle static const int scaleShift = 16; static const kint32 scale = (1 << scaleShift); static const kint32 scaleBitmask = scale - 1; static const kint32 halfScale = scale / 2; static const double dInvScale = 1. / scale; - const kint32 det_dx = nearest (xInc * sin (theta) / detInc * scale); - const kint32 det_dy = nearest (yInc * cos (theta) / detInc * scale); + const kint32 det_dx = nearest (xInc * cos (theta) / detInc * scale); + const kint32 det_dy = nearest (yInc * sin (theta) / detInc * scale); // calculate L for first point in image (0, 0) kint32 detPosColStart = nearest ((start_r * cos (theta - start_phi) / detInc + iDetCenter) * scale); @@ -624,3 +632,82 @@ BackprojectIntDiff3::BackprojectView (const double* const filteredProj, const do } //end linear } // end for ix } + + +void +BackprojectEquiangular::BackprojectView (const double* const filteredProj, const double view_angle) +{ + double beta = view_angle; + + for (int ix = 0; ix < nx; ix++) { + ImageFileColumn pImCol = v[ix]; + + for (int iy = 0; iy < ny; iy++) { + double dAngleDiff = beta - phi[ix][iy]; + double rcos_t = r[ix][iy] * cos (dAngleDiff); + double rsin_t = r[ix][iy] * sin (dAngleDiff); + double dFLPlusSin = m_dFocalLength + rsin_t; + double gamma = atan (rcos_t / dFLPlusSin); + double dL2 = dFLPlusSin * dFLPlusSin + (rcos_t * rcos_t); + + if (interpType == Backprojector::INTERP_NEAREST) { + int iDetPos =iDetCenter + nearest(gamma / detInc); // calc index in the filtered raysum vector + + if (iDetPos < 0 || iDetPos >= nDet) { // check for impossible: index outside of raysum pos + ; // errorIndexOutsideDetector (ix, iy, beta, r[ix][iy], phi[ix][iy], gamma, iDetPos); + } else + pImCol[iy] += filteredProj[iDetPos] / dL2; + } else if (interpType == Backprojector::INTERP_LINEAR) { + double dPos = gamma / detInc; // position along detector + double dPosFloor = floor (dPos); + int iDetPos = iDetCenter + static_cast(dPosFloor); + double frac = dPos - dPosFloor; // fraction distance from det + if (iDetPos < 0 || iDetPos >= nDet - 1) { + ; // errorIndexOutsideDetector (ix, iy, beta, r[ix][iy], phi[ix][iy], gamma, iDetPos); + } else + pImCol[iy] += (((1-frac) * filteredProj[iDetPos] + frac * filteredProj[iDetPos+1])) / dL2; + } + } // end for y + } // end for x +} + +void +BackprojectEquilinear::BackprojectView (const double* const filteredProj, const double view_angle) +{ + double beta = view_angle; + + for (int ix = 0; ix < nx; ix++) { + ImageFileColumn pImCol = v[ix]; + + for (int iy = 0; iy < ny; iy++) { + double dAngleDiff = beta - phi[ix][iy]; + double rcos_t = r[ix][iy] * cos (dAngleDiff); + double rsin_t = r[ix][iy] * sin (dAngleDiff); + + double dU = (m_dFocalLength + rsin_t) / m_dFocalLength; + double dDetPos = rcos_t / dU; + // double to scale for imaginary detector that passes through origin + // of phantom, see Kak-Slaney Figure 3.22 + dDetPos *= 2; + + if (interpType == Backprojector::INTERP_NEAREST) { + int iDetPos = iDetCenter + nearest(dDetPos / detInc); // calc index in the filtered raysum vector + + if (iDetPos < 0 || iDetPos >= nDet) // check for impossible: index outside of raysum pos + ; /// errorIndexOutsideDetector (ix, iy, beta, r[ix][iy], phi[ix][iy], dDetPos, iDetPos); + else + pImCol[iy] += (filteredProj[iDetPos] / (dU * dU)); + } else if (interpType == Backprojector::INTERP_LINEAR) { + double dPos = dDetPos / detInc; // position along detector + double dPosFloor = floor (dPos); + int iDetPos = iDetCenter + static_cast(dPosFloor); + double frac = dPos - dPosFloor; // fraction distance from det + if (iDetPos < 0 || iDetPos >= nDet - 1) + ; // errorIndexOutsideDetector (ix, iy, beta, r[ix][iy], phi[ix][iy], dDetPos, iDetPos); + else + pImCol[iy] += (((1-frac) * filteredProj[iDetPos] + frac * filteredProj[iDetPos+1])) / (dU * dU); + } + } // end for y + } // end for x +} +