[Insight-users] itkGradientDifferenceImageToImageMetric

[Karthik Krishnan]

It looks like a bug . Please log an entry in the bug tracker.

thanks
karthik

Vicente Grau wrote:

> I have been comparing several image-to-image metrics using a 
> modification of the program MeanSquaresImageMetric1.cxx. With 
> GradientDifferenceImageToImageMetric, I get a constant value, 
> independent of the translation between the images (e.g., in case of 
> two 3D images, 40x60x60 voxels, intensity range 0-255, the value is 
> always 339204.)
> I have only found an example that uses this metric, it is one of the 
> tests of itkAlgorithmsTests2.exe. When I run it, I get the result 
> below. It seems to me that this result has exactly the same problem: 
> the same value 20000 regardless of the translation values (and 
> derivatives equal to 0). Is this the expected result for this test? Is 
> the metric working well?
>
> ------------------------
> Available tests:
> ...
> 3. itkGradientDifferenceImageToImageMetricTest
> ...
> To run a test, enter the test number: 3
>
> Parameters: [-50, -50], Value: 20000, Derivatives: [0, 0]
> Parameters: [-25, -50], Value: 20000, Derivatives: [0, 0]
> Parameters: [0, -50], Value: 20000, Derivatives: [0, 0]
> Parameters: [25, -50], Value: 20000, Derivatives: [0, 0]
> Parameters: [50, -50], Value: 20000, Derivatives: [0, 0]
> Parameters: [-50, -25], Value: 20000, Derivatives: [0, 0]
> Parameters: [-25, -25], Value: 20000, Derivatives: [0, 0]
> Parameters: [0, -25], Value: 20000, Derivatives: [0, 0]
> Parameters: [25, -25], Value: 20000, Derivatives: [0, 0]
> Parameters: [50, -25], Value: 20000, Derivatives: [0, 0]
> Parameters: [-50, 0], Value: 20000, Derivatives: [0, 0]
> Parameters: [-25, 0], Value: 20000, Derivatives: [0, 0]
> Parameters: [0, 0], Value: 20000, Derivatives: [0, 0]
> Parameters: [25, 0], Value: 20000, Derivatives: [0, 0]
> Parameters: [50, 0], Value: 20000, Derivatives: [0, 0]
> Parameters: [-50, 25], Value: 20000, Derivatives: [0, 0]
> Parameters: [-25, 25], Value: 20000, Derivatives: [0, 0]
> Parameters: [0, 25], Value: 20000, Derivatives: [0, 0]
> Parameters: [25, 25], Value: 20000, Derivatives: [0, 0]
> Parameters: [50, 25], Value: 20000, Derivatives: [0, 0]
> Parameters: [-50, 50], Value: 20000, Derivatives: [0, 0]
> Parameters: [-25, 50], Value: 20000, Derivatives: [0, 0]
> Parameters: [0, 50], Value: 20000, Derivatives: [0, 0]
> Parameters: [25, 50], Value: 20000, Derivatives: [0, 0]
> Parameters: [50, 50], Value: 20000, Derivatives: [0, 0]
> GradientDifferenceImageToImageMetric (0198CE00)
>  RTTI typeinfo:   class 
> itk::GradientDifferenceImageToImageMetric<class 
> itk::Image<double,2>,class itk::Image<double,2> >
>  Reference Count: 1
>  Modified Time: 50
>  Debug: Off
>  Observers:
>    none
>  ComputeGradient: 1
>  Moving Image: 0198A938
>  Fixed  Image: 0198CAA0
>  Gradient Image: 019C85A0
>  Transform:    01987800
>  Interpolator: 019C82B0
>  FixedImageRegion: ImageRegion (0198CE54)
>  Dimension: 2
>  Index: [0, 0]
>  Size: [100, 100]
>
>  Moving Image Mask: 00000000
>  Fixed Image Mask: 00000000
>  Number of Pixels Counted: 0
> Test passed.
>
>
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