[Insight-developers] backward compatibility issue with new streaming support

[Bradley Lowekamp]

Also how does it not work now? Error message? invalid data? etc?

I found this innocent change could cause erroneous output under these conditions. The output would not be in the correct byte orders. Is that the problem you are experiencing?

http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/IO/itkMetaImageIO.cxx?root=Insight&r1=1.101&r2=1.102

Brad

On Dec 11, 2009, at 10:19 AM, Lowekamp, Bradley (NIH/NLM/LHC) [C] wrote:

> What version were you upgrading from and to?
> 
> Is it all readers that broke for you or just MetaImageIO?
> 
> I am sorry that these changes broke your code, I tried very hard to ensure that the interface was backwards compatible.
> 
> Brad
> 
> On Dec 11, 2009, at 10:00 AM, M.Staring at lumc.nl wrote:
> 
>> Dear developers,
>> 
>> In our institute (LKEB) we sometimes use the ITK image IO classes
>> without using the itk::ImageFileReader. (This way we can e.g. directly
>> read in the data buffer into our own image type: lkebImage.)
>> 
>> We recently updated the underlying ITK to a more recent version, and
>> found out that it did not work anymore. The reason it does not work are
>> the changes that were made to support streaming. A new member m_IORegion
>> was added to the class ImageIOBase; it's constructor initializes that
>> member to a 2D region of size [0 0]. The framework now expects that this
>> m_IORegion is set externally, which in the ITK is done in the
>> ImageFileReader (line 389 of the txx). However, we do not use the
>> ImageFileReader and therefore our code breaks.
>> 
>> To fix this issue I would expect that the m_IORegion is by default set
>> to the largest possible region (or the requested region) and not to size
>> 0. I'm not sure if it is the best place to fix this, but this could be
>> fixed by adapting the Read() or ReadImageInformation()-functions of all
>> ImageIO's that support streaming. For example MetaImageIO::Read() could
>> check if m_IORegion was manually set, and if not set it to the requested
>> region. Something like:
>> 
>> if ( !m_IORegionManuallySet ) // or: if ( m_IORegion.GetSize() == 0 )
>> {
>> m_IORegion = m_RequestedRegion; // or: m_IORegion =
>> m_LargestPossibleRegion;
>> }
>> 
>> and then proceed ...
>> 
>> What do you think ?
>> 
>> Regards,
>> 
>> Marius
>> 
>> 
>> Marius Staring, PhD
>> Division of Image Processing (LKEB)
>> Department of Radiology
>> Leiden University Medical Center
>> PO Box 9600, 2300 RC Leiden, The Netherlands
>> phone: +31 (0)71 526 1106, fax: +31 (0)71 526 6801
>> m.staring at lumc.nl
>> 
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> 
> _______________________________________________
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> 
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> 
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