[Insight-users] fixed and moving image

[kevin cavin]

Hi, Markus: 

      Thanks for your reply.  what your explanation is clear. Actually the reason I ask this question is just because I found that If I change the two images ( fixed and moving ) I  could obtain different results. Therefore I come up the question. 

      It seems for me that if you want register one image with another one, and  if you do not want the orginal one is modified , the you should set that one as fixed since the moving image will be resampled and interpolated. But sometime it seems that  setting the orginal image as fixed image can not get registeration result as good as it has been set as moving image. 

     Maybe  you have some extra thought about that. 


Kind regards 

calvin  




--- On Tue, 9/29/09, Markus Neuner <neuner.markus at gmx.net> wrote:

From: Markus Neuner <neuner.markus at gmx.net>
Subject: Re: [Insight-users] fixed and moving image
To: "kevin cavin" <beibeiwen2003 at yahoo.com>
Cc: insight-users at itk.org
Date: Tuesday, September 29, 2009, 8:13 PM

Hi Calvin,

In general the goal of registration is to find the transform that will bring a moving image into alignment with a fixed image based on the used registration criteria (maximize/minimize).
The transform maps points from the fixed image space to the moving image space.

Fixed image:
One or more fixed images are the reference of registration. It remains unchanged. The moving image is registered to match the fixed image.

Moving image:
The moving image is re-sampled to match the fixed image. Interpolation is performed in the moving image.

Which image is used as fixed and moving image heavily depends on the application. What images do you register (Size, Spacing, ...), and what is the desired goal of your registration?
If you change the two images you could obtain different results, especially when the spacings/sizes of th e images differ.


Best Regards,
Markus




kevin cavin wrote:
> Hello,
> 
> I am working with ITK at this moment. I have one question regarding the selection of fixed and moving images. Does it matter that which one is fixed and which one is moving. Are there any rules for that? I noticed normally the moving image will be interpolated. Thanks !
> 
> 
> sincerely
> 
> calvin
> 
> 
> 



      
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