[Insight-developers] Policy about filter behavior

[Miller, James V (CRD)]

Filters should be designed to operate over a specified region.  However, there are cases where this
is not possible (FFT is a good example).  For these cases, the specified filter can override
ProcessObject::EnlargeOutputUpdateExtent() and ProcessObject::ComputeInputUpdateExtent() as needed to
change the default behavior.

The implementations of these routines may change over the next couple of weeks, however, the
capability to change how much a filter needs as input or will produce as output will remain.

Note, the "extent" ivars in DataObject are not currently used by Image. We are trying to rework the
nomenclature so that it is easier to understand what routines a filter writer is responsible for.

We also need to put out a document describing the development path when a filter cannot simply
process the specified region.

For now, just make sure your filters can process a region independent of the update mechanism.  We'll
get the update mechanism in shape and report back.

Jim

-----Original Message-----
From: Josh Cates [mailto:cates at rolle.engr.utk.edu]
Sent: Tuesday, August 29, 2000 12:46 PM
To: luis.ibanez at ieee.org
Cc: insight-developers at public.kitware.com
Subject: Re: [Insight-developers] Policy about filter behavior


On Tue, 29 Aug 2000, Luis Ibanez wrote:
> 
> 2) The second question is related with the required initialization
> of the images and with the requirements for streaming
> 
> Is the filter supposed to work over the Buffer,
> over the entire Image, or over a Region ?

My understanding is that the filter should be designed to work over the
Region.

A related question that I have is:  How can a filter request a larger
Region (Buffer) from its inputs (i.e. suppose an algorithm needs the whole
image as a Region).  Is this handled automatically or must it be managed
by the pipeline architect (user)?

Josh.
 



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 Josh Cates			
 Dept. of Electrical Engineering	
 University of Tennessee, Knoxville
 Email: jecates at utk.edu
 Phone: (865) 974-0694
 URL:   www.cs.utk.edu/~cates
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