[Insight-developers] in place filters

[Luis Ibanez]

Hi Henning,


This is what the Image Adaptors do. They generate their input
on the fly without having to allocate memory for it.


Please read the ITK Software Guide

         http://www.itk.org/ItkSoftwareGuide.pdf


In particular Chapter 12: "Image Adaptors", in pdf-page 777-788


You will find source code examples in the directory:


          Insight/
             Examples/
                DataRepresentation/
                                Image/
                                  ImageAdaptors*.cxx



Note that the current implementation only works for pixel-wise
filters.



     Regards,


        Luis



====================
Henning Meyer wrote:
> But I meant a completely different thing. A filter, which does not
> overwrite its input, but generates its output on the fly.
> 
> Henning
> 
> 2006/7/13, Miller, James V (GE, Research) <millerjv at crd.ge.com>:
> 
>> Many ITK filters can run in place.  Those that can derive from 
>> InPlaceImageFilter
>> (which is a subclass of ImageToImageFilter). There are two constraints 
>> for in place
>> filtering.  First, the input and output image must be the same 
>> dimension (2D, 3D, etc.).
>> Second, the input and output image must have the same pixel type 
>> (short, double, etc.).
>>
>> If these conditions are met, then the InPlace filter will manage the 
>> memory buffers so
>> that ownership of the pixel container passes from the input image to 
>> the output image
>> and no additional storage is allocated.  If these conditions are not 
>> met, then the
>> InPlaceFilter falls back to behaving like an ImageToImageFilter.
>>
>> An InPlaceFilter must call the method AllocateOutputs() (on itself) in 
>> its GenerateData()
>> method instead of calling Allocate() directly on the output image.
>>
>> Many filters are already subclasses of InPlaceImageFilter. But there 
>> are probably many
>> filters in ITK that should be subclasses of InPlaceImageFilter that 
>> are not currently.
>> If you identify any such filters, please let us know and we will look 
>> into making
>> those filters run in place.
>>
>> /** \class InPlaceImageFilter
>>  * \brief Base class for filters that take an image as input and 
>> overwrite that image as the output
>>  *
>>  * InPlaceImageFilter is the base class for all process objects whose
>>  * output image data is constructed by overwriting the input image
>>  * data. In other words, the output bulk data is the same block of
>>  * memory as the input bulk data.  This filter provides the mechanisms
>>  * for in place image processing while maintaining general pipeline
>>  * mechanics. InPlaceImageFilters use less memory than standard
>>  * ImageToImageFilters because the input buffer is reused as the
>>  * output buffer.  However, this benefit does not come without a cost.
>>  * Since the filter overwrites its input, the ownership of the bulk
>>  * data is transitioned from the input data object to the output data
>>  * object.  When a data object has multiple consumers with one
>>  * of the consumers being an in place filter, the in place filter
>>  * effectively destroys the bulk data for the data object. Upstream
>>  * filters will then have to re-execute to regenerate the data object's
>>  * bulk data for the remaining consumers.
>>  *
>>  * Since an InPlaceImageFilter reuses the input bulk data memory for the
>>  * output bulk data memory, the input image type must match the output
>>  * image type.  If the input and output image types are not identical,
>>  * the filter reverts to a traditional ImageToImageFilter behaviour
>>  * where an output image is allocated.  In place operation can also be
>>  * controlled (when the input and output image type match) via the
>>  * methods InPlaceOn() and InPlaceOff().
>>  *
>>  * Subclasses of InPlaceImageFilter must take extra care in how they
>>  * manage memory using (and perhaps overriding) the implementations of
>>  * ReleaseInputs() and AllocateOutputs() provided here.
>>  *
>>  * \ingroup ImageFilters
>>  */
>>
>>
>> -----Original Message-----
>> From: insight-developers-bounces+millerjv=crd.ge.com at itk.org
>> [mailto:insight-developers-bounces+millerjv=crd.ge.com at itk.org]On Behalf
>> Of Henning Meyer
>> Sent: Thursday, July 13, 2006 3:29 AM
>> To: insight-developers at public.kitware.com
>> Subject: [Insight-developers] in place filters
>>
>>
>> Hello,
>>
>> when working with large volumes it's quite annoying that itk filters
>> reserve an extra memory block to store the filtered image.
>> Would'nt it be nice to have filters which work in place? This idea
>> could be combined with the IteratorTraits idea and sparse volumes very
>> nicely. And if used correctly filter could still be chained. However,
>> I think one would loose the flexibility to change filters at runtime -
>> but honestly - who is doing this anyway?
>>
>> Henning
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>>
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