From f1831812306ad7114fcd94618cc2857bb63c8fc1 Mon Sep 17 00:00:00 2001
From: "Kevin M. Rosenberg" <kevin@rosenberg.net>
Date: Sun, 3 Dec 2000 15:16:18 +0000
Subject: [PATCH] r234: Fixed scaling bug with redundant rotations around
 phantom

---
 ChangeLog                   |  1 +
 include/backprojectors.h    |  4 ++--
 libctsim/backprojectors.cpp | 13 +++++++------
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 582e251..876515c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,7 @@
    Fixed minor compilation problem with procsignal.h
    Updated README file
    Fixed bug when simulating projections and Trace == CONSOLE
+   Fixed scaling bug when performing redundant rotations around object
 	
 2.0.5 - 12/01/00
    Improved compilation on RedHat 7
diff --git a/include/backprojectors.h b/include/backprojectors.h
index ef70d05..e3418df 100644
--- a/include/backprojectors.h
+++ b/include/backprojectors.h
@@ -9,7 +9,7 @@
 **  This is part of the CTSim program
 **  Copyright (C) 1983-2000 Kevin Rosenberg
 **
-**  $Id: backprojectors.h,v 1.15 2000/09/02 05:10:39 kevin Exp $
+**  $Id: backprojectors.h,v 1.16 2000/12/03 15:16:17 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
@@ -126,7 +126,7 @@ class Backproject
     kint32 nx;
     kint32 ny;
     double detInc;
-    double rotInc;
+    double rotScale;
     int iDetCenter;      	// index refering to L=0 projection 
     int nDet;
     double xMin, xMax, yMin, yMax;     // Retangular coords of phantom
diff --git a/libctsim/backprojectors.cpp b/libctsim/backprojectors.cpp
index 8c785ac..152e026 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 1.14 2000/09/02 05:10:39 kevin Exp $
+**  $Id: backprojectors.cpp,v 1.15 2000/12/03 15:16:18 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
@@ -262,7 +262,8 @@ 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 
-  rotInc = proj.rotInc();
+  rotScale = proj.rotInc();
+  rotScale /= (proj.nView() * proj.rotInc() / PI); // scale by number of PI rotations
 
   v = im.getArray();
   nx = im.nx();
@@ -288,7 +289,7 @@ Backproject::ScaleImageByRotIncrement ()
 {
   for (int ix = 0; ix < nx; ix++)
     for (int iy = 0; iy < ny; iy++)
-      v[ix][iy] *= rotInc;
+      v[ix][iy] *= rotScale;
 }
 
 void Backproject::errorIndexOutsideDetector (int ix, int iy, double theta, double r, double phi, double L, int iDetPos)
@@ -335,7 +336,7 @@ BackprojectTrig::BackprojectView (const double* const filteredProj, const double
 	if (iDetPos < 0 || iDetPos >= nDet)	// check for impossible: index outside of raysum pos 
 	    errorIndexOutsideDetector (ix, iy, theta, r, phi, L, iDetPos);
 	else
-	  v[ix][iy] += rotInc * filteredProj[iDetPos];
+	  v[ix][iy] += rotScale * filteredProj[iDetPos];
       } else if (interpType == Backprojector::INTERP_LINEAR) {
 	  double p = L / detInc;	// position along detector
 	  double pFloor = floor (p);
@@ -344,7 +345,7 @@ BackprojectTrig::BackprojectView (const double* const filteredProj, const double
 	  if (iDetPos < 0 || iDetPos >= nDet - 1) 	// check for impossible: index outside of raysum pos 
 	    errorIndexOutsideDetector (ix, iy, theta, r, phi, L, iDetPos);
 	  else
-	    v[ix][iy] += rotInc * ((1-frac) * filteredProj[iDetPos] + frac * filteredProj[iDetPos+1]);
+	    v[ix][iy] += rotScale * ((1-frac) * filteredProj[iDetPos] + frac * filteredProj[iDetPos+1]);
       }
     }
   }
@@ -493,7 +494,7 @@ BackprojectDiff2::BackprojectView (const double* const filteredProj, const doubl
   double detPosColStart = start_r * cos (theta - start_phi) / detInc;
 	
 #ifdef DEBUG
-  printf ("start_r=%8.5f, start_phi=%8.5f, rotInc=%8.5f\n", start_r, start_phi, rotInc);
+  printf ("start_r=%8.5f, start_phi=%8.5f, rotScale=%8.5f\n", start_r, start_phi, rotScale);
 #endif
   for (int ix = 0; ix < nx; ix++, detPosColStart += det_dx) {
     double curDetPos = detPosColStart;
-- 
2.34.1