[Insight-developers] Change to itkMultiResolutionPyramidImageFilter.txx

[Bradley Lowekamp]

I have just been asking for a clarification of what this bug means.  
Based on Han's response:


>> Brad,
>>
>> The problem is that the origin is not properly computed in the down  
>> sampled images, and the origin affects the location.
>>
>> Hans

These changes:
http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Algorithms/itkMultiResolutionPyramidImageFilter.txx?root=Insight&r1=1.25&r2=1.28
http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Algorithms/itkRecursiveMultiResolutionPyramidImageFilter.txx?root=Insight&r1=1.15&r2=1.16
in fact, these changed don't effect the origin or the location of the  
image. So I really don't understand what was trying to be achieved here.


To add more to the confusion the description Luis added for the patch  
doesn't seem right either:
http://public.kitware.com/Bug/view.php?id=8795

The change from shrinker to a linear resampler is arbitrary, ill  
motivated, and changes the intrinsic behavior of these filter. These  
changes did not solve the bug and are quickly creating a nest of  
confusing mantis entries! With many people working on individual  
problems, and no one looking at the big picture.

Hopefully there is a TCON tomorrow. I think it would be best if this  
could be discussed there, to determine what the correct behaviors and  
and what should be done.

Brad

On Mar 26, 2009, at 6:02 PM, kent williams wrote:

> Brad, the switch to ResampleImageFilter to ShrinkImageFilter  
> occurred n 12-17-2008, and are part of the 3.12 release.  The small  
> change I checked in this week — which Luis is back-porting into 3.12  
> — just turns off UseImageSpacing, which was the default behavior  
> prior to 12-18-2008.
>
>
> I changed RecursiveMultiResolutionPyramidImageFilter this week to  
> also use ResampleImageFilter in preference to ShrinkImageFilter.    
> This was a change requested after some discussion, and logged in the  
> Bug Tracker:
> http://public.kitware.com/Bug/view.php?id=8482
>
>
> This change did not break any existing regression tests.  Obviously,  
> it would be good to have a regression test that failed before this  
> change and succeeds afterwards.  When Hans gets back in the office  
> next week, I’ll discuss formulating such a test.
>
> Conversely, if this change introduces some behavior you find  
> undesirable it would be great if you could come up with a test  
> program that illustrates the problem.
>
>
> I don’t have a dog in this fight, I just try to fix the bugs I’m  
> assigned without breaking anything obvious.  I studied Comp Sci and  
> not Medical Image Processing background so every time I tackle one  
> of these filters, I don’t even necessarily know what it does  
> beforehand, or have any idea what would constitute improved or  
> impaired behavior.

I must ask then why are you trying to fix it if you don't know what is  
broken or what is correct?

>
>
> On 3/26/09 4:43 PM, "Hans Johnson" <hans-johnson at uiowa.edu> wrote:
>>
>
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