is there a way to set custom metric in itk registration in python?

sedghi · February 23, 2018, 5:09pm

I have a similarity metric that I’d like to use in ImageRegistrationMethod in itk python, is there any way to do so?

matt.mccormick · February 23, 2018, 7:33pm

Yes. If it is an existing method in ITK, it can be used from Python with the ImageRegistrationMethod.

If it is a new method you created your self, you can quickly wrap it in Python, and create an installable Python Package. More information:

The ITK Module Template. This will get you going with a skeleton module in two commands.
The ITK Software Guide’s chapter on How to Create A Module. This includes instruction on how to add wrapping.

Please let us know if you have any questions.

sedghi · February 23, 2018, 7:39pm

Thanks @matt
actually my custom made metric is implemented in python. Do I still need to create an installable python package?

sedghi · April 20, 2018, 2:34pm

@matt.mccormick
I was wondering if there is any update on this issue?
Is there any python callable (function) for the optimizer interface right now?

matt.mccormick · April 20, 2018, 6:14pm

@sedghi There is not a python callable (function) interface to supply your own method right now, but that is a great idea. @pieper has been thinking about it, too.

I don’t think it is that hard to implement. What do you think about an itk.PythonImageRegistrationMetricv4 class? This class would be similar to itk.ImageToImageMetricv4, but it would have additional methods,

GetValuePythonCallback
GetDerivativePythonCallback
GetValueAndDerivativePythonCallback

These methods would be passed Python functions that accept the ImageToImageMetricv4 as an argument and would need to return required value and derivative values.

pieper · April 21, 2018, 3:26pm

Sounds great @matt.mccormick! Yes, @sedghi and I worked together looking into this so hopefully he can let us know if these methods would be enough to cover the use case.

kayarre · November 12, 2019, 2:18am

Any progress on this front?

matt.mccormick · November 12, 2019, 4:40pm

I created this issue for tracking:

Note that we have similar functionality to define an image filter in Python:

github.com

InsightSoftwareConsortium/ITK/blob/master/Wrapping/Generators/Python/PyUtils/itkPyImageFilter.h

/*=========================================================================
 *
 *  Copyright Insight Software Consortium
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 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
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 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
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 *=========================================================================*/

#ifndef itkPyImageFilter_h
#define itkPyImageFilter_h

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