[Insight-developers] Adding Consistency check to itk::BinaryFunctorImageFilter : Design Question

[Gaëtan Lehmann]

Le 2 déc. 09 à 23:39, Luis Ibanez a écrit :

> Gaetan,
>
> That's a very good point.
>
> The method should indeed be available at a higher level
> in the filter hierarchy. Probably at the level of the
>
>                 itkImageToImageFilter
>
> How about offering a method that does:
>
>    bool CheckImageInformationConsistency(
>         const ImageBase * image1,
>         const ImageBase * image2
>         ) const;
>
> This could still use helper method for specific
> comparisons, such as
>
>    bool CheckImageSpacingConsistency(
>         const ImageBase * image1,
>         const ImageBase * image2
>         ) const;
>
> ...
>
> bool CheckImageOriginConsistency( ...)
> bool CheckImageDirectionConsistency(...)
>
> ....
>
>
> Looking at what we are comparing, this is all
> information that is available at the level of the
> ImageBase, therefore we may manage to base
> it only on the image dimension.
>
> Filters down the hierarchy could use these
> methods in different combinations, according
> to what applies to their particular cases.
>
> BTW: one concern is that the Origin, Spacing
> and Direction comparisons may have to be
> made with a certain numerical tolerance.
>
>

Good point - it may avoid some unpleasant error messages when working  
with resample images for example.

>
> What do you think ?

That looks great :-)

Gaëtan


>
>
>       Thanks
>
>
>               Luis
>
>
>
> -----------------------------------------------------
> 2009/12/2 Gaëtan Lehmann <gaetan.lehmann at jouy.inra.fr>:
>>
>> Hi Luis,
>>
>> I personally prefer your first approach. Don't you think that
>> CheckInputImagesConsistency() should be in  
>> BeforeThreadedGenerateData() in
>> BinaryFunctorImageFilter directly, instead of its subclasses? The  
>> tests may
>> be desactivated in the subclasses if needed, by reimplementing
>> BeforeThreadedGenerateData().
>>
>> Also, this bug must also be in many other classes which are  
>> processing
>> several inputs - maybe those methods should be added in a more  
>> basic class,
>> so they can be reused in those filters as well?
>>
>> Gaëtan
>>
>>
>> Le 2 déc. 09 à 21:12, Luis Ibanez a écrit :
>>
>>> The Bug 9893:
>>>
>>>           http://www.itk.org/Bug/view.php?id=9893
>>>
>>> calls for adding a check of consistency between the two input
>>> images of filters that derive from itkBinaryFunctorImageFilter.
>>>
>>> The example, is the AddImageFilter, in which we implicitly
>>> assume that the two images passed as input have:
>>>
>>>   1) The same number of pixels along each dimension
>>>   2) The same origin
>>>   3) The same spacing
>>>   4) The same direction
>>>
>>>
>>> Currently there is no check for these assumption,
>>> and therefore, a user can pass two images of different
>>> sizes, and get a segmentation fault at run time.
>>>
>>> ---
>>>
>>> The proposed fix is to add the following methods:
>>>
>>>>  /** These method verify if the two input images have the same
>>>>  *  size, origin, spacing and orientation. It is intended to be
>>>>  *  called from some derived filters, when they require the two
>>>>  *  inputs to be consistent. The method throws and exception if
>>>>  *  the two input images are not consistent. */
>>>>  void CheckInputImagesConsistency();
>>>>  void CheckInputImagesConsistencyInSize();
>>>>  void CheckInputImagesConsistencyInOrigin();
>>>>  void CheckInputImagesConsistencyInSpacing();
>>>>  void CheckInputImagesConsistencyInDirection();
>>>
>>>
>>> to the protected section of the itkBinaryFunctorImageFilter.
>>>
>>>
>>> Then, most of its derived classes will call the method:
>>>
>>>           CheckInputImagesConsistency()
>>>
>>>
>>> (which internally will call all the other methods, each one
>>> of which could throw an exception if the consistency check
>>> fails).
>>>
>>>
>>> Particular filters that do not require all checks, could call
>>> only those that apply.
>>>
>>> The suggested place to make these calls is the method
>>>
>>>                BeforeThreadedGenerateData();
>>>
>>>
>>> ---
>>>
>>> An alternative approach is to set these calls in the
>>> itkBinaryFunctorImageFilter, and add a boolean that
>>> sets whether the check should be performed or not.
>>>
>>> Derived filters could then set that boolean in their
>>> constructors.
>>>
>>> ----
>>>
>>>
>>> Any preferences between the two approaches above ?
>>>
>>> Any objections ?
>>>
>>> or Backward Compatibility concerns ?
>>>
>>>
>>>    Thanks
>>>
>>>
>>>         Luis
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>>
>> --
>> Gaëtan Lehmann
>> Biologie du Développement et de la Reproduction
>> INRA de Jouy-en-Josas (France)
>> tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
>> http://voxel.jouy.inra.fr  http://www.itk.org
>> http://www.mandriva.org  http://www.bepo.fr
>>
>>

-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr  http://www.itk.org
http://www.mandriva.org  http://www.bepo.fr

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