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0004962

ITK

public

2007-05-02 10:45

2007-09-17 10:20

Reporter

Ivan Macia

Assigned To

Julien Jomier

Priority

normal

Severity

major

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

Target Version

Fixed in Version

Summary

0004962: Error in normalization in itk::GaussianDerivativeSpatialFunction

Description

In file itkGaussianDerivativeSpatialFunction when using m_Normalized to calculate a gaussian of unit area, the normalization factor seems to be wrong. According to what I expect (see attached document) the lines

if (m_Normalized)
{
  prefixDenom = m_Sigma[0]*m_Sigma[0]*m_Sigma[0];
  for(unsigned int i = 1; i < VImageDimension; i++)
  {
    prefixDenom *= m_Sigma[i]*m_Sigma[i]*m_Sigma[i];
  }

  prefixDenom *= 2 * 3.1415927;
}

should be replaced by

if (m_Normalized)
{
  prefixDenom = m_Sigma[m_Direction]*m_Sigma[m_Direction]

  for(unsigned int i = 0; i < VImageDimension; i++)
    prefixDenom *= m_Sigma[i];

  prefixDenom *= vcl_pow( 2 * 3.1415927, VImageDimension / 2.0);
}

Also in line 78 multiplying by 2 at the beginning is not correct.

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Attached Files

NormalizedGaussianDerivatives.pdf [^] (21,791 bytes) 1969-12-31 19:00

Relationships

Notes
(0009016) Luis Ibanez (manager) 2007-09-17 10:20	The fix was committed by Julien: http://www.itk.org/cgi-bin/viewcvs.cgi/Code/Common/itkGaussianDerivativeSpatialFunction.txx?root=Insight&r1=1.7&r2=1.8 [^]

Issue History
Date Modified	Username	Field	Change
2007-09-17 10:20	Luis Ibanez	Note Added: 0009016