[Insight-developers] Re: Adaptor update mechanism

[Karthik Krishnan]

Hi Jim,

Thanks again for looking at this. As you just mentioned, that does solve 
the the problem too.  The ComputeOffset() function in ImageBase.h would 
then need an extra line
    m_BufferedRegion = this->GetBufferedRegion();

With this solution there is an implementation issue though. 
ComputeOffset() is meant to be a const method.

Thanks
Regards
karthik


Miller, James V (Research) wrote:

>Karthik, 
>
>That is probabaly a reasonable fix. I am still not sure why it should
>matter whether the ImageAdapter has a proper m_BufferedRegion.  If all
>access to m_BufferedRegion is via GetBufferedRegion(), the adaptor 
>should have delegated down to the internal image.  The only place
>I saw that m_BufferedRegion was accessed directly was in ComputeOffsetTable(), 
>ComputeOffset() and ComputeIndex() (all in ImageBase).
>
>Did you try changing these methods to call GetBufferedRegion()
>instead of accessing m_BufferedRegion directly?
>
>That being said, it is probably best that the BufferedRegion ivar 
>in the ImageAdaptor be kept consistent with the underlying image.
>So calling this->SetBufferedRegion( m_Image->GetBufferedRegion() )
>is a good idea.
>
>Jim
>
>
>
>-----Original Message-----
>From: Karthik Krishnan [mailto:Karthik.Krishnan at kitware.com]
>Sent: Wednesday, June 01, 2005 1:04 PM
>To: Miller, James V (Research)
>Cc: Insight-developers (E-mail); Luis Ibanez
>Subject: Re: Adaptor update mechanism
>
>
>Hi Jim,
>
>Thank you very much for looking at it.
>
>The changes I was thinking of in the last mail were incorrect. I think 
>I've found it now though.
>
>First, I re-ran the example on Linux and on VS71 and ImageAdaptor2 
>crashes if reader->Update() is not called prior to adaptor->SetImage(). 
>
>As you mentioned, the m_BufferedRegion was not being set correctly, 
>because the ImageAdaptor calls SetBufferedRegion() only in the function 
>SetImage(). So, if a pipeline is set-up prior to execution, I don't see 
>how the buffered region could be propagated correctly.
>
>I did fix it though by adding SetBufferedRegion( 
>m_Image->GetBufferedRegion() ) right after the m_Image updates its 
>output data.
>
>So  ImageAdaptor::UpdateOutputData() would be :
>
>ImageAdaptor<TImage , TAccessor>::UpdateOutputData()
>{
>  // call the superclass' method first, then delegate
>  Superclass::UpdateOutputData();
>
>  // delegation to internal image
>  m_Image->UpdateOutputData();
>  SetBufferedRegion( m_Image->GetBufferedRegion() );
>}
>
>That fixes it, but I am not sure if it is the correct thing to do.
>
>Thanks
>regards
>karthik
>
>PS: Here were the command line params I used to run ImageAdaptor2 (with 
>nightly CVS source)
>~/work/ITK/binaries/Insight/Nightly/bin/ImageAdaptor2 
>~/work/ITK/src/Insight/Nightly/Examples/Data/VisibleWomanEyeSlice.png 
>redEye.png
>
>
>Miller, James V (Research) wrote:
>
>  
>
>>Karthik, 
>>
>>I'd have to look at this in more detail.  Your suggested changes do not seem
>>correct to me.  
>>
>>ImageAdaptor2 works fine for me if I remove the call to reader->Update().
>>(Using .Net 2003).
>>
>>The LargestPossibleRegion and the RequestedRegion should have been propagated
>>through the adaptered already.  If there is a problem, it might be somewhere 
>>where m_BufferedRegion is accessed directly instead of via an access method.
>>
>>The only place I see this happening is in ComputeOffsetTable(). We could have
>>that method call GetBufferedRegion().  However, I cannot duplicate the error 
>>you are getting.
>>
>>
>>Jim
>>
>>
>>-----Original Message-----
>>From: Karthik Krishnan [mailto:Karthik.Krishnan at kitware.com]
>>Sent: Tuesday, May 31, 2005 5:22 PM
>>To: Insight-developers (E-mail); Luis Ibanez; Miller, James V (Research)
>>Subject: Adaptor update mechanism
>>
>>
>>Hi,
>>
>>The adaptors don't seem to propagate information when plugged into the 
>>pipeline. For example ImageAdaptor2 example segfaults if 
>>reader->Update() is commented out.
>>
>>I believe that  the Update() call in ImageAdaptor.txx should be
>>
>>//----------------------------------------------------------------------------
>>template <class TImage, class TAccessor >
>>void
>>ImageAdaptor<TImage , TAccessor>
>>::Update()
>>{
>> Superclass::Update();
>>
>> Superclass::SetLargestPossibleRegion( 
>>m_Image->GetLargestPossibleRegion() );
>> Superclass::SetBufferedRegion( m_Image->GetBufferedRegion() );
>> Superclass::SetRequestedRegion( m_Image->GetRequestedRegion() );
>> m_Image->Update();
>>}
>>
>>instead of what it is now. Please correct me if I am mistaken. I don't 
>>want to commit incorrect code since I am not familiar enough with the 
>>pipeline mechanism.
>>
>>Thanks
>>Regards
>>Karthik
>>
>>
>> 
>>
>>    
>>
>
>  
>