This directory contains source code for building MEX files
that do the back-projection step of the FDK (Feldkamp, Davis, Kress)
cone-beam image reconstruction method.

Individuals working with this may want to see the original 1984 paper:
http://dx.doi.org/10.1364/JOSAA.1.000612

However, the "notation" in the software may not match that paper.
The notation matches a book chapter on tomography that JF has written.
Ask JF for this chapter if interested.


fdk-orig/
The "current" version for a "standard" CPU.

Other directories contain versions that try to accelerate computation
by using CUDA on GPU.
To compile those versions you will probably
need to modify one of the Makefiles to use the paths
to your installation of the CUDA library from Nvidia.

http://developer.nvidia.com/object/matlab_cuda.html


After compiling to make fdk_mex.mex[suffix]
you can test your compiled version by using the matlab command:
        cbct_back test
If your path is correct, this will try to compare the version in jf_mex.mex*
with the version fdk_mex.mex* that is in your local directory or path,
checking for numerical consistency between these versions.
You should see lines like the following:

cbct_back_test: found fdk_mex:
 /Volumes/a2/fessler/src/matlab/alg/mex/src/fdk/fdk-orig/fdk_mex.mexmaci64
cbct_back_test: mpd jf_mex vs fdk_mex: 0.328966%

Hopefully your "maximum percent difference" (mpd) error is < 1% or so.


After you have debugged your code you are ready to compare the compute times.
For this comparison, use the routine:

	cbct_back_time

You can edit your own local copy of this routine to change parameters.

2010-06-23
The latest matlab version (2010a?) does not include the file "mexversion.c"
in extern/src, so I modified script
	ir62:/usr/local/matcuda/nvmex
to eliminate the dependency on it.
Also, the 64-bit version of the cuda library are in $(CUDAHOME)/lib64
so I modified the Makefile to use
	-L$(CUDAHOME)/lib64
instead of
	-L$(CUDAHOME)/lib


More versions have been added by various students.
I need to clean up and document them better...
The newest versions are:
fdk-cuda-wei
fdk-cuda-wu,meng


Also see the version branched off by Miriam Leeser's group at Northeastern:
http://www.coe.neu.edu/Research/rcl/projects/CBCT.php