[Insight-users] NormalizedCorrelationImageToImageMetric speedup

[Andinet Enquobahrie]

> Hi Andinet,
>
> I was afraid I had to do that :) But see
>
>    
> http://www.insightsoftwareconsortium.org/InsightJournal/view_reviews.php?back=index.php&pubid=87 
>
>
> for the description and the source code.
>
> Marius


Great! thanks a lot

-Andinet

>
>
> Andinet Enquobahrie wrote:
>
>> Hi Marius,
>>
>> Can you please write a short description of your improvements to the 
>> NormalizedCorrelationImageToImageMetric class and submit your 
>> description with the code to the InsightJournal.
>>
>> http://insightsoftwareconsortium.org/InsightJournal/
>>
>> thank you
>>
>> -Andinet
>>
>>> Hi all,
>>>
>>> The current GetDerivative() and GetValueAndDerivative() from the 
>>> NormalizedCorrelationImageToImageMetric loop twice over the fixed 
>>> image. This is not neccesary, one time is enough to calculate the 
>>> metric value and the derivative to the transform parameters. I have 
>>> rewritten this class to do so, and this gives the expected (almost) 
>>> two times speedup.
>>>
>>> Also I have added the possibility to compute the metric over only a 
>>> random subset of the fixed image pixels. This reduces the 
>>> computation time (substantially), while convergence properties are 
>>> maintained. It is similar to the MattesMutualInformationMetric, but 
>>> there a fixed subset is used.
>>>
>>> I have added this code as an attachment. Feel free to commit it to 
>>> the repository (the code also contains some small bug fixes). I have 
>>> tested that, when using all pixels in the fixed image, the new code 
>>> gives exactly the same output as the current itk code.
>>>
>>> I have also implemented the possibillity to use a random subset in 
>>> the MeanSquaresImageToImageMetric (shouldn't that be called the 
>>> MeanSquareDifferenceImageToImageMetric?) This is also attached.
>>>
>>> Regards,
>>>
>>> ------------------------------------------------------------------------ 
>>>
>>>
>>> _______________________________________________
>>> Insight-users mailing list
>>> Insight-users at itk.org
>>> http://www.itk.org/mailman/listinfo/insight-users
>>>  
>>>
>>
>>
>>
>