[Insight-developers] Change to itkMultiResolutionPyramidImageFilter.txx

[Bill Lorensen]

The Shrinker changes were in part meant to maintain alignment of the
centr's of the subsample volume with the original volume.

As for performance, we should benchmark the old and new versions with
optimized compilations on a couple of platforms.

Bill

On Thu, Mar 26, 2009 at 5:34 PM, Bradley Lowekamp
<blowekamp at mail.nih.gov> wrote:
> 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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