[Insight-users] Bug with fix Mean Image Filter

[Miller, James V (Research)]

FixedArray is the superclass of Vector.  Vectors (and Points and Covariant vector) add semantics to a FixedArray. For instance, a Vector is used to represent a direction. A Point is used to represent a position. A FixedArray is just a collection of values with not semantics.
 
 

-----Original Message-----
From: Bradley Lowekamp [mailto:blowekamp at mail.nih.gov]
Sent: Wednesday, May 18, 2005 12:33 PM
To: Miller, James V (Research)
Cc: insight-users at itk.org
Subject: Re: [Insight-users] Bug with fix Mean Image Filter




it.Set( static_vast<OutputPixelType>(sum * ( 1.0 / double(neighbothoodSize))) ); 


That should work too. But I think that it is an oversite that NumericTraits<RGBPixel> does not have ScalarRealType. 


With regards to the added operator to RGBPixel (and likely for RGBAPixel too), I am still confused about the differences between FixedArray and Vector classes. I think I read in the Software Guide instances where each were used, though I can't seemed to find an example of FixedArray at the moment. The Vector class provides many math operators so I also don't understand why they specific pixel types were not derived from the Vector class. 



Thanks. 


======================================================== 

Bradley Lowekamp 

Management Systems Designers Contractor for 

Office of High Performance Computing and Communications 

National Library of Medicine 

'blowekamp at mail.nih.gov 



On May 18, 2005, at 9:22 AM, Miller, James V ((Research)) wrote: 


Can you use: 





A better option is probably to add scalar division (by a floating point type) to the RGBPixel type. 



Jim 

-----Original Message----- 

From: insight-users-bounces+millerjv=crd.ge.com at itk.org [mailto:insight-users-bounces+millerjv=crd.ge.com at itk.org]On Behalf Of Bradley Lowekamp 

Sent: Tuesday, May 17, 2005 4:58 PM 

To: insight-users at itk.org 

Subject: [Insight-users] Bug with fix Mean Image Filter 



I was trying to use mean Image Filter with RGBPixel Type. This failed because this pixel type did not supported the needed operator. This was the line 




// get the mean value 


it.Set( static_vast<OutputPixelType>(sum / double(neighbothoodSize)) ); 




RGBPixels do not support the divide by scalars operator. Perhaps because this type may have only been designed to used with unsigned chars? Any way the fix I coded up was: 



// get the mean value 


it.Set( static_vast<OutputPixelType>(sum * (1.0/NumericTraits<OutputPixelType>::ScalarRealType(neighbothoodSize))) ); 




However, that didn't work because NumericTraits<RGBPixel<unsigned char>> does not have a ScalarRealType member, like every other numeric traits. I actually am using RGBPixelType<double> but I implemented the numeric traits my self. 



Thanks. 





======================================================== 


Bradley Lowekamp 


Management Systems Designers Contractor for 


Office of High Performance Computing and Communications 


National Library of Medicine 


'blowekamp at mail.nih.gov

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