From 558820f1421e79b32e542c133c83683e58df6d5e Mon Sep 17 00:00:00 2001
From: Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl>
Date: Fri, 24 Jun 2016 15:28:47 +0200
Subject: Compute FBP filter in spatial domain
---
cuda/2d/fft.cu | 46 +++++++++++++++++++++++++++++++++++++++-------
1 file changed, 39 insertions(+), 7 deletions(-)
(limited to 'cuda/2d')
diff --git a/cuda/2d/fft.cu b/cuda/2d/fft.cu
index 2bfd493..2d259a9 100644
--- a/cuda/2d/fft.cu
+++ b/cuda/2d/fft.cu
@@ -35,6 +35,7 @@ $Id$
#include <fstream>
#include "../../include/astra/Logging.h"
+#include "astra/Fourier.h"
using namespace astra;
@@ -303,16 +304,48 @@ void genFilter(E_FBPFILTER _eFilter, float _fD, int _iProjectionCount,
float * pfFilt = new float[_iFFTFourierDetectorCount];
float * pfW = new float[_iFFTFourierDetectorCount];
+ // We cache one Fourier transform for repeated FBP's of the same size
+ static float *pfData = 0;
+ static int iFilterCacheSize = 0;
+
+ if (!pfData || iFilterCacheSize != _iFFTRealDetectorCount) {
+ // Compute filter in spatial domain
+
+ delete[] pfData;
+ pfData = new float[2*_iFFTRealDetectorCount];
+ int *ip = new int[int(2+sqrt(_iFFTRealDetectorCount)+1)];
+ ip[0] = 0;
+ float32 *w = new float32[_iFFTRealDetectorCount/2];
+
+ for (int i = 0; i < _iFFTRealDetectorCount; ++i) {
+ pfData[2*i+1] = 0.0f;
+
+ if (i & 1) {
+ int j = i;
+ if (2*j > _iFFTRealDetectorCount)
+ j = _iFFTRealDetectorCount - j;
+ float f = M_PI * j;
+ pfData[2*i] = -1 / (f*f);
+ } else {
+ pfData[2*i] = 0.0f;
+ }
+ }
+
+ pfData[0] = 0.25f;
+
+ cdft(2*_iFFTRealDetectorCount, -1, pfData, ip, w);
+ delete[] ip;
+ delete[] w;
+
+ iFilterCacheSize = _iFFTRealDetectorCount;
+ }
+
for(int iDetectorIndex = 0; iDetectorIndex < _iFFTFourierDetectorCount; iDetectorIndex++)
{
float fRelIndex = (float)iDetectorIndex / (float)_iFFTRealDetectorCount;
- // filt = 2*( 0:(order/2) )./order;
- pfFilt[iDetectorIndex] = 2.0f * fRelIndex;
- //pfFilt[iDetectorIndex] = 1.0f;
-
- // w = 2*pi*(0:size(filt,2)-1)/order
- pfW[iDetectorIndex] = 3.1415f * 2.0f * fRelIndex;
+ pfFilt[iDetectorIndex] = 2.0f * pfData[2*iDetectorIndex];
+ pfW[iDetectorIndex] = M_PI * 2.0f * fRelIndex;
}
switch(_eFilter)
@@ -866,5 +899,4 @@ void downloadDebugFilterReal(float * _pfHostSinogram, int _iProjectionCount,
free(pfHostFilter);
}
-
#endif
--
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