[Insight-developers] iterator without index efficiency problem

[Miller, James V (GE, Research)]

Gaetan, 

Where are your timing comparisons between the iterator types?

We have studied the performance of the iterators several times.  The last 
in depth study was a several years ago.  Maybe something has changed.

In previous studies, we ran both sets of iterators over a common task.
While the program did report a difference in iterator timings, if we 
switched which iterator performed the task first, the timings would 
flip, leading to a different conclusion.

To accumulate over different dimensions, you might want to consider the 
ImageLinearConstIteratorWithIndex.  Depending on how you are accumulating
the information along a direction, this iterator may be more effecient than
a ImageRegionIterator or a ImageRegionIteratorWithIndex.

I'll out together a test on the iterator performance so that we can 
benchmark the iterators.

Jim

-----Original Message-----
From: insight-developers-bounces+millerjv=crd.ge.com at itk.org
[mailto:insight-developers-bounces+millerjv=crd.ge.com at itk.org]On Behalf
Of Gaetan Lehmann
Sent: Monday, February 20, 2006 7:57 AM
To: insight-developers at itk.org
Subject: [Insight-developers] iterator without index efficiency problem



Hi,

I have noted a huge difference fo efficiency between the iterator with or  
without index: the iterator with index is more efficient than the one  
without index.
Is it a known problem ?
I'm using ITK2.4.1. Is is still valid in ITK cvs ? If yes, it should be  
fixed before the 2.6 release.
I have noticed that while working of projections. Timing test can be ran  
to reproduce that.
http://insight-journal.org/view_reviews.php?back=index.php&pubid=71

Reagards,

Gaetan

-- 
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
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