[Insight-users] Streaming and memory allocation

[Will Schroeder]

I have sent a preliminary pdf document; let me know if anyone else wants a 
peek.
Will

At 07:31 AM 6/5/2002 -0700, Jarek Sacha wrote:
>I am trying to figure out how streaming works in ITK and write some
>streaming applications. I see how a 'RequestedRegion' can be pulled
>through a pipeline during processing (StreamingImageFilter).
>
>I have problem figuring out, however, what is the process of allocating
>the memory for streaming. Memory allocation is critical since in most
>streaming applications you want to do processing using amount of memory
>that is a fraction of the size of the image that is being process. For
>instance, I want to do processing on an image that is 6GB while my RAM is
>only 1GB.
>
>Here are some issues that I see as roadblocks of proper memory allocation
>or as my lack of understanding what is going on:
>
>1) Image objects tend to allocate memory for the LargestPossibleRegion
>rather then BufferedRegion, see ImageBase< >::UpdateOutputInformation()
>
>2) ImageFileReader<>::GenerateOutputInformation() forces allocation of
>memory buffer equal to input image size.
>
>3) Allocation is performed during GenerateOutputInformation, which is
>before information about RequestedRegion is pushed up the pipeline
>
>4) StreamingImage filter does not overwrite GetInputRequestedRegion,
>rather this method is called from ImageToImageFilter and in turn from
>ProcessObject that calls an all inputs
>SetRequestedRegionToLargestPossibleRegion()
>
>Could somebody give me some clues how memory allocation for streaming
>works?
>
>Jarek
>
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