[Insight-users] Garbage Collection Problem with Python WrapITK

[Chapman, Brian]

I have run across a major difference with how WrapITK behaves on Mac OSX and
on Centos linux. I've primarily been developing on Mac OSX where the
behavior is as I would expect. I can create a function that creates an ITK
image and then returns the image to the calling function. Everything works
beautifully. However, in Centos any object created in a function fails to
persist when it is returned to the calling function. To test that this is a
WrapITK problem, I wrote a simple function which creates a numarrray object
and then returns the numarray object to the calling function. On both Mac
OSX and Centos this works correctly.

A simple function which creates an ITK image, however, behaves differently
in OSX than it does in Centos. Here is the program:

import numarray as na
import numarray.mlab as mlab
import numarray.random_array as ra
import itk

def test1(dim = [16,128,128]):
    img = ra.normal(5,2,shape=dim)
    return img

def test2(img):
    sc = itk.ShiftScaleImageFilter.IF3IF3.New()
    sc.SetInput(img)
    sc.SetShift(0)
    sc.SetScale(2)
    sc.Update()
    img = sc.GetOutput()
    return img
def main():
    img = test1()
    print "min(img)=%f, max(img)=%f"%(mlab.min(img.flat),mlab.max(img.flat))

    reader = itk.ImageFileReader.IF3.New(FileName='test.mha')
    reader.Update()
    img = reader.GetOutput()
    print itk.range(img)
    img2 = test2(img)
    print itk.range(img2)

if __name__=='__main__':
    main()

Here is the output on OSX:

cbmi01:~/Code/Python/Multispectral brian$ python testMem.py
min(img)=-4.767438, max(img)=14.360112
(0.0, 1895.0)
(0.0, 3790.0)
cbmi01:~/Code/Python/Multispectral brian$

Here is the output on Centos:
[brian at DBMI-MDT-044 Multispectral]$ python testMem.pymin(img)=-4.801929,
max(img)=14.282335
(0.0, 1895.0)
Segmentation fault

Any ideas about what is going on? I'd appreciate your help.

Brian