[Insight-users] UnaryFunctorImageFilter and MetaDataDictionnary

[Bill Lorensen]

This would be implemented for all DataObjects.

GDCMImageIO already produces a heavyweight image. Currently no one
except IO readers/writers are using the meta data dictionary, although
abuse is possible.

Propagation would be the same as is dome for CopyInformation.

And, this is still in the thought provoking, discussion stage.

Bill

On Tue, Oct 27, 2009 at 1:00 PM, Karthik Krishnan
<karthik.krishnan at kitware.com> wrote:
> Is this supported only for UnaryFunctorImageFilters or for all
> ProcessObjects ? Is it an overridable method ?
>
> Mutli-input filters ? for instance a CT image masked by a mask. Does
> it propagate from the first input ?
> Is the API "PassMetaDataDictionaryFromNthInputToMthOutputOn( n, m )"
> preferred to "PassMetaDataDictionaryOn()" ?
>
> If supported at the DataObject level, what happens in cases where the
> objects aren't  images ? eg. processobjects that generate transforms
> as outputs / other decorated DataObjects ?
>
> Will a DICOM reader produce a heavyweight dictionary and add bloat to
> lightweight outputs ?
>
> One would worry that parameters from the metadatadic will by used by
> users in lieu of an input parameter within the library because once
> supported, there's room for misuse, lack of type safety.. ?
>
> thanks
>
>
> On Tue, Oct 27, 2009 at 11:35 AM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>> I don't think we need another dictionary. As Jim Miller noted in the
>> original bug report
>> http://public.kitware.com/Bug/view.php?id=4625
>>
>> we could copy the dictionary in the CopyInformation method in ProcessObject.
>>
>> I just checked all of the itk Code/ directories. For the most part,
>> only IO classes use or encapsulate meta data dictionary information.
>>
>> I think we can safely copy the meta data dictionary as Jim suggested.
>>
>> I'll investigate further.
>>
>>
>> On Tue, Oct 27, 2009 at 10:32 AM, Julien Michel <julien.michel at c-s.fr> wrote:
>>> Bill Lorensen a écrit :
>>>>
>>>> Another possibility is for the application to observe the EndEvent of
>>>> the filters and copy the input meta data dictionary to the output of
>>>> the filter. We might be able to package this into a helper class.
>>>>
>>>> I'll look into this one.
>>>
>>> Bill,
>>>
>>> Sometimes we want to have access to these meta-information even-though the
>>> filter execution has not yet been triggered (for instance we do not need to
>>> process the whole image just to access its ground control points). That is
>>> why this solution seems incomplete to me (but I might be wrong).
>>>
>>> If you want to make it clear that the beyond the customization point it is
>>> the user responsibility to ensure data consistency, why not add a second
>>> metadata dictionnary (for instance m_UserDefinedDictionnary) along with its
>>> methods (virtual void GenerateOutputUserDefinedDictionnary()), with a
>>> default implementation copying from first input to outputs ?
>>>
>>> This way it is clear that these members are provided for customization and
>>> that they are the users responsibility (and it does not modify any of the
>>> existing ITK functionalities).
>>>
>>> Julien
>>> --
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> Julien MICHEL - Ingénieur d'études - Traitement d'images
>>> CS Systèmes d'Information - Division ESPACE
>>> Département Information Géographique & Image
>>> Téléphone : +33 561 17 64 27
>>> Email : julien.michel at c-s.fr
>>>
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>>
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