BUG: Limits check in ComputeJacobianWithRespectToPosition

If the point was assumed to be inside the image (tested independently), the absolute value applied to index was unnecessary.
And by removing the absolute value we get also the checking for the index being inside.

Added the starting index of the LargestPossibleRegion to make the algorithm also valid for non-zero starting index.

Modules/Filtering/DisplacementField/include/itkDisplacementFieldTransform.hxx

@@ -224,6 +224,7 @@ DisplacementFieldTransform<TParametersValueType, NDimensions>::ComputeJacobianWi
 {
 
   typename DisplacementFieldType::SizeType    size = this->m_DisplacementField->GetLargestPossibleRegion().GetSize();
+  typename DisplacementFieldType::IndexType   startingIndex = this->m_DisplacementField->GetLargestPossibleRegion().GetIndex();
   typename DisplacementFieldType::SpacingType spacing = this->m_DisplacementField->GetSpacing();
 
   IndexType ddrindex;
@@ -237,7 +238,7 @@ DisplacementFieldTransform<TParametersValueType, NDimensions>::ComputeJacobianWi
   TParametersValueType space = NumericTraits<TParametersValueType>::OneValue();
 
   // Minimum distance between neighbors
-  TParametersValueType mindist = NumericTraits<TParametersValueType>::OneValue();
+  IndexValueType mindist = NumericTraits<IndexValueType>::OneValue();
 
   // Flag indicating a valid location for Jacobian calculation
   bool isValidJacobianCalcLocat = true;
@@ -247,12 +248,12 @@ DisplacementFieldTransform<TParametersValueType, NDimensions>::ComputeJacobianWi
   dPixSign = doInverseJacobian ? -dPixSign : dPixSign;
   for (unsigned int row = 0; row < NDimensions; ++row)
   {
-    TParametersValueType dist = itk::Math::abs((float)index[row]);
+    IndexValueType dist = index[row] - startingIndex[row];
     if (dist < mindist)
     {
       isValidJacobianCalcLocat = false;
     }
-    dist = itk::Math::abs((TParametersValueType)size[row] - (TParametersValueType)index[row]);
+    dist = static_cast<IndexValueType>(size[row]) - dist;
     if (dist < mindist)
     {
       isValidJacobianCalcLocat = false;