[ITK-users] [ITK] Getting info from a very big image file

[Lowekamp, Bradley (NIH/NLM/LHC) [C]]

Gib,

I have not tested this, but the LSMImageIO is derived from the TIFFImageIO,  and LSMImageIO::Read does just call TIFFImageIO. So the chances are very good that it supports streamed reading.

I updated the TIFFImageIO to support stream reading of the individual pages in the TIFF stack some time ago.

You may find the following example useful to determining if the functionality is there:
https://github.com/InsightSoftwareConsortium/ITK/blob/master/Examples/IO/ImageReadExtractWrite.cxx


You can see the usage of “UpdateOutputInformation” followed by the ExtractImageFilter, this can be a very powerful and efficient pattern for working with large images. The ExtractImageFilter can be used to create a 3D to 2D image from it’s input volume.

Brad


On 12/11/17, 10:56 PM, "Matt McCormick" <matt.mccormick at kitware.com> wrote:

    Hi Gib,
    
    Call
    
     reader->UpdateOutputInformation();
    
    instead of
    
      reader->Update();
    
    to get the LargestPossibleRegion populated without loading the pixel buffer.
    
    
    The image IO has to support streaming to read in only a
    RequestedRegion -- unfortunately, I do not think the LSMImageIO
    supports this at this time.
    
    HTH,
    Matt
    
    On Mon, Dec 11, 2017 at 10:44 PM, Gib Bogle <g.bogle at auckland.ac.nz> wrote:
    > Hello,
    >
    >
    > I am wanting to work with a 50 GB LSM file (3D).  The first step is to be
    > able to get the image info: width, height and depth.  I have code that works
    > on a small LSM file
    >
    >
    >     im_u16 = reader->GetOutput();
    >     width = im_u16->GetLargestPossibleRegion().GetSize()[0];
    >     height = im_u16->GetLargestPossibleRegion().GetSize()[1];
    >     depth = im_u16->GetLargestPossibleRegion().GetSize()[2];
    >
    >
    > but I see that to do this the whole image must be loaded into memory.  When
    > I start the program running with the big file I can see that it is going to
    > exceed the host machine's 32 GB.  Is there a way to get the image dimensions
    > without loading the whole image?  What I am hoping to do is split the file
    > into 2D TIFF files - is there any way to extract a 2D slice without reading
    > the whole image?  Or will I be forced to run on a  machine with more than 50
    > GB of RAM?
    >
    >
    > Thanks in advance for any suggestions.
    >
    >
    > Best regards
    >
    > Gib
    >
    >
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