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List:       insight-users
Subject:    Re: [ITK-users] Mattes Mutual Information can produce a false positive?
From:       David Welch <david.m.welch () gmail ! com>
Date:       2015-12-16 17:55:39
Message-ID: 79DC6C6D-D325-48E3-8F34-3FE0F614ABF2 () urthecast ! com
[Download RAW message or body]

Hi Gabriel, 

I'm a little rusty, so maybe someone else can correct my example.

1) Consider a circle with one half "dark: and one half "bright" with a gray \
background.  2) Then consider the inverted image (max() - image).
3) Rotate the inverted image randomly about the center.
4) Now register the two using Mattes'.  

Do you see the problem? Statistically, both pairings of bright->bright and \
bright->dark have the same entropy to Mattes', so neither would be preferred and the \
algorithm would settle on which ever solution it reaches first and would give a false \
positive 50% of the time.  

So Mattes' CAN produce false positives depending on the underlying statistics for the \
image pairs.

Cheers,
Dave 




On 12/15/15, 2:25 PM, "Gabriel A. Giménez" <gabrielgimenez85@gmail.com> wrote:

> Hi all, I hope you are well...
> 
> My question is about a implementation of Mattes Mutual Information...is
> possible to produce a false positive ? at times it gives me a high metric
> value ... but the result of the recording is poor. We use it as a metric for
> two implementations of optimizers (PSO and Scatter search).
> 
> Attached results of two executions, using scatter search:
> 
> Moving image: mr_pd
> Fixed image: ct
> Images source: http://www.insight-journal.org/rire/download_data.php
> (patient_001)
> 
> Thank you very much and I hope you can help me, regards.
> 
> 
> ct_mr_pd_incorrect_result.zip
> <http://itk-insight-users.2283740.n2.nabble.com/file/n7588261/ct_mr_pd_incorrect_result.zip> \
>  ct_mr_pd_accurate_result.zip
> <http://itk-insight-users.2283740.n2.nabble.com/file/n7588261/ct_mr_pd_accurate_result.zip> \
>  
> 
> 
> --
> View this message in context: \
> http://itk-insight-users.2283740.n2.nabble.com/Mattes-Mutual-Information-can-produce-a-false-positive-tp7588261.html
>  Sent from the ITK Insight Users mailing list archive at Nabble.com.
> 

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