[ITK] [ITK-users] Mattes Mutual Information can produce a false positive?

[David Welch]

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 at 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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