[Insight-users] noise and normalized correlation

[Romain Lebel]

Hello everyone!
I'm currently testing the normalized correlation metric on my 
registration problem
I need to register an image on another knowing that the moving image 
translates, and that there is a small scale on the image. The moving 
image is captured at a different height so it is defocused (implies a 
bluring)
I'm using the affin transform with the optimizerscaleparameter[1] and 
[2] to a great value so that no rotation is possible (i used to set them 
to 1 and i had a big shearing effect does anyone faced this?)
I'm using the RegularStepGradientDescentOptimizer and linear interpolator.
I tried it on very simple synthesis images and it works fine. But when i 
add noise on them the translation is ok but the scaling is wrong (even 
when i filter the images using a median filter)
Is this metric very sensitiv to noise or does it come from the optimizer?
Or maybe the cause is ohterwhere....?

-- 
Romain Lebel
PhaseView - Telecom Paris
37-39 rue Dareau, 75014 Paris
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