[Insight-developers] image information reset by gradient magnitude filter

[Bill Lorensen]

I agree we should collect these testing utilities into a common place.

Brad,

What do you mean about --compare? Do you mean that it should also
check the image information? I think that would be easy to add.
However, it would not have detected the bug we just found.

Bill

On Thu, Feb 5, 2009 at 11:16 AM, Bradley Lowekamp
<blowekamp at mail.nih.gov> wrote:
> Hello,
> I have a comment about testing.
>
> I am very surprised that Bill had to implement an ImageInformationIsEqual
> function to compare. I had to implement a methods to method to compare
> images from memory and files based on the DifferenceImageFilter. It really
> seems like there should be a common place for these kinds of methods ( and
> classes like itkPipelineMonitorImageFilter :) And other easy and standard
> ways to verify the execution and output of a pipeline. Has anyone else
> noticed that  the standard --compare flag for tests  doesn't verify the
> geometry is correct? </gripe>
> Brad
>
>
> On Feb 5, 2009, at 10:49 AM, Gaëtan Lehmann wrote:
>
> Hi,
>
> Le 5 févr. 09 à 16:29, Bill Lorensen a écrit :
>
> Luis,
>
> This error has always been present I believe.
>
> I reproduced the problem using CVS HEAD. I modified the filter's test
>
> by adding non-default image information to the test input. Then, after
>
> the filter runs, I compared the input and output image information.
>
> Before my fix, the information differed. You can duplicate the failure
>
> with my new test, if you comment out my fix (one line) and re-run the
>
> test.
>
> This filter creates an internal image to accumulate results over each
>
> dimension. Since the internal image never copied the image information
>
> from the input image, the internal image had default settings for the
>
> information. This internal image was used as the input to a mini
>
> pipeline. The output of the internal mini-pipeline is grafted onto the
>
> output of the filter.
>
> This design has not always been there. I have introduced it to add the
> multithreading support.
>
> http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/BasicFilters/itkGradientMagnitudeRecursiveGaussianImageFilter.txx?root=Insight&r1=1.18&r2=1.19
>
> The changes looked quite simple and not dangerous to me. The lack of
> failing test has comforted me in that opinion.
> That bug show that I was wrong.
>
> My apologies for that bug.
>
> Gaëtan
>
>
> --
> Gaëtan Lehmann
> Biologie du Développement et de la Reproduction
> INRA de Jouy-en-Josas (France)
> tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
> http://voxel.jouy.inra.fr  http://www.mandriva.org
> http://www.itk.org  http://www.clavier-dvorak.org
>
> <PGP.sig><ATT00001.txt>
>
> ========================================================
>
> Bradley Lowekamp
>
> Lockheed Martin Contractor for
>
> Office of High Performance Computing and Communications
>
> National Library of Medicine
>
> blowekamp at mail.nih.gov
>
>
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