[Insight-users] Reading portion of the image without loading the whole image into the memory

[yan xu]

 Hi, David,
        I'm afraid it doesn't work, the codes are following for 16bit nrrd.
The memory still increases up to the size of the image not the region of
image I defined. Is it due to the image type or something? The codes are
following:

UShortImageType::IndexType index;
index[0] = startX;
index[1] = startY;
 index[2] = startZ;

UShortImageType::SizeType size;
size[0] = sizeX;
 size[1] = sizeY;
size[2] = sizeZ;

UShortImageType::RegionType region;
 region.SetIndex( index);
region.SetSize( size);

ushortImageReader::Pointer reader = ushortImageReader::New();
 reader->SetFileName(fileName);
reader->GetOutput()->SetRequestedRegion(region);

try
{
reader->Update();
 }
catch ( itk::ExceptionObject &err)
{
 std::cout << "Error in bin_image_writer: " << err << std::endl;
}


Yan

On Tue, Aug 14, 2012 at 4:08 PM, David Doria <daviddoria at gmail.com> wrote:

> On Tue, Aug 14, 2012 at 4:59 PM, yan xu <xy198908 at gmail.com> wrote:
>
>> Hi, all
>>       I'm facing a problem to read only portion of the image to test the
>> algorithm since the whole image is too big for the memory. I have tried
>> using the itk pipeline through extractimage filter, but I don't think it
>> works. The memory still goes larger and larger. My image type is 16bit
>> nrrd. What I hope is that the only the desired region of the image is
>> loaded into the memory. Is there a solution for that? Thank you!
>>
>
> I've never done it, but you could try this:
>
> http://www.itk.org/Wiki/ITK/Examples/SimpleOperations/RequestedRegion
>
> on your ImageReader.
>
> David
>



-- 
Yan Xu
Research Assistant
Bio-Image Analytics Laboratory
Department of Electrical and Computer Engineering
University of Houston
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