ENH: compare outputs of itkResampleImageTest2Streaming to determine success

[romangrothausmann]

relates to #392
and intends to not only take the return value into account but also the comparison of the output with the expected results.

@thewtex in relation to #392 (comment): Since it is necessary for streaming to write to MHAs (not PNGs as originally the case), the output is uncoupled from itkResampleImageTest2, so I guess we do not need the DEPENDS property.
I am not sure though if it is critical that the second input comes from PNG circle.png, which is not available as MHA. I noticed that you changed the first input from PNG to MHA cthead1.mha. Is that necessary for successful streaming and would the same apply for the reference image?
Just using cthead1.mha as second input again is probably not good in conjunction with the comparison because there would be no resampling if the reference image is the same as the main input.

[thewtex]

@romangrothausmann awesome, thanks for the follow-up! 💯 🥇

Yes, if the outputs and inputs of the tests are independent, we do not need the DEPENDS property. 👍

Since PNG's cannot stream, the entire image will be read on the first pipeline update -- we should use MHA for these streaming tests.

[romangrothausmann]

Since PNG's cannot stream, the entire image will be read on the first pipeline update -- we should use MHA for these streaming tests.

OK, so either adding a circle.mha to the set of input data or using cthead1.mha also as the 2nd input but then all expected output MHAs would need to be updated and I have doubts that this will lead to actual resampling (not sure about the itkResampleImageFilter details there), since circle.png is used by the other itkResampleImageTest2 tests. So I would g for the first option, if you agree.

[thewtex]

+1 for adding circle.mha.

It can be generated with:

import itk
image = itk.imread('circle.png')
itk.imwrite(image, 'circle.mha')

Then, upload the data.

[thewtex]

Rebasing on master...

[dzenanz]

Tests are now passing

[thewtex]

Merging...