[Insight-users] Re: ITK Configuration
Luis Ibanez
luis.ibanez@kitware.com
Thu May 20 16:37:33 EDT 2004
Hi Shekhar,
1) "Parameters setting" is the fundamental flaw of
any attempt to compare methods in image processing.
It seems that the community hasn't recognized
yet the fact that parameters are integral part
of a method. In some way the parameter values
*are* part of the code.
There are no standard configurations for
registration. The best that you can do is
a) Select a *very specific* image
registration problem.
b) Take a registration method configuration
and fine tune its full set of parameters
until you get the best results you can
find.
c) Take another registration method configuration
and again fine tune its full set of parameters
until you get the best results
d) Compare the results of (b) and (c) in terms
of computational time and stability, (e.g.
sensibility to variations in the parameters).
Note that the conclusions that you can draw at
the end are of the type:
Method A *with* this set of parameters behave
better than Method B *with* this other set
of parameter when registering *this* specific
pair of images.
Any gratuitous generalization of the type
"Method A is better than Method B"
will only be good for 'publishing a paper'...
2) Please read the chapter on Multi-Resolution
image registration in the SoftwareGuide
http://www.itk.org/ItkSoftwareGuide.pdf
the number of levels you define in the MultiResolution
registration method is not the number of pyramids to
use. The number of pyramids is *always* two. The value
is used to define how many levels to use in those two
pyramids.
3) Please read the chapter above....
and try the associated examples in
Insight/Examples/Registration/
MultiResImageRegistration1.cxx
MultiResImageRegistration2.cxx
4) NormalizedMutualInformation is available in ITK
http://www.itk.org/Insight/Doxygen/html/classitk_1_1NormalizedMutualInformationHistogramImageToImageMetric.html
Please consult the Doxygen documentation whenever
you are looking for specific methods in ITK. The
best places to look are:
http://www.itk.org/Insight/Doxygen/html/classes.html
and
http://www.itk.org/Insight/Doxygen/html/modules.html
5) Please read the Chapter on image registration in
the SoftwareGuide. You will find there indications
on how to set optimizer parameters.
You may find also interesting to look at the
course on Image Registration Techniques
http://www.cs.rpi.edu/courses/spring04/imagereg/
In particular to lectures 7,8,9 and 10.
If you have questions about a *specific* optimizer
please let us know.
Regards,
Luis
-------------------------------------------
Dwivedi, Shekhar (Research, Non-ge) wrote:
> Hi luis,
>
> there are few doubts , please help me.
>
> 1- If we are comparing various optimizers or metrics or filters, then what is the standard configuration on whose basis we will change other parameters, I mean that there must be some parameters which should be fixed at a time and others should change. e.g. At a time either we use single image registration or multi image registration and then the paramteres are changed.
>
> 2- The number of levels which we declare in the multi Image registration is the number of Image pyramids we are to consider or something else.IF we set the number of levels as 1 then will it be same as single image registration (means no pyramid of images).
>
> 3- If we set the number of levels as 2 then only initialization of the pyramid filter will mean that registration will take care of generating the pyramids(gaussians) or we have to specify the parameters of the same.
>
> 4- Is Normalised Mutual Information implemented in ITK.
>
> 5- As for each optimizer , every parameter is not set for registration unlike as stated in the test cases, can I found any documentation which helps me in understanding the parameters effecting in specific Image registration.
>
> yours,
> shekhar.
>
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