[Insight-developers] Histogram::GetIndex() boundary conditions

[Stephen R. Aylward]

I agree.   Often histograms have open tails...perhaps that should be the 
default.   Regardless, having the low values index the upper bin and 
having inconsistent behavior seems like a mistake.

Stephen

Miller, James V (Research) wrote:
> I was recently looking through the code for itk::Histogram and noticed blocks of code like
> 
>     if (tempMeasurement < m_Min[dim][begin])
>       {
>       // one of measurement is below the minimum
>       m_TempIndex[dim] = (long) m_Size[dim] ;
>       itkWarningMacro(<<"One of the measurement components is below the minimum");
>       }
> 
> and 
> 
>     if (tempMeasurement < m_Min[dim][begin])
>       {
>       // one of measurement is below the minimum
>       index[dim] = (long) m_Size[dim] ;
>       return false;
>       }
> 
> and similar code for when the index exceeds the maximum bounds.
> 
> The first block of code was from GetIndex(const MeasurementVectorType& measurement) and the second was from GetIndex(const MeasurementVectorType & measurement, IndexType & index).
> 
> In the former case, a component of the index is set and the procedure continues along it way.  In the second case, a component is set and the routine returns.
> 
> Should the latter return before it has the opportunity to set the rest of the components of the index?
> 
> Is the index component value correct for these cases?  In both exceeding the minimum and maximum bounds, the index component is set to m_Size[dim].  I am assuming this indicates a bin that is outside the histogram.  I would have guessed that specifying a measurement that was below the first bin would put that measurement in the first bin and that specifying a measurement that is above the last bin would put that measurement in the last bin.
> 
> Jim
> 
> 
> 
> 
> Jim Miller 
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> 
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-- 
===========================================================
Dr. Stephen R. Aylward
Associate Professor of Radiology
Adjunct Associate Professor of Computer Science and Surgery
http://caddlab.rad.unc.edu
aylward at unc.edu
(919) 966-9695