# vtkImageDifference does not detect different images

**URL:** <https://discourse.vtk.org/t/vtkimagedifference-does-not-detect-different-images/12935>\
**Category:** Development\
**Created:** [December 19, 2023, 3:10pm UTC](https://discourse.vtk.org/t/vtkimagedifference-does-not-detect-different-images/12935 "2023-12-19T15:10:17Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Yohann\_Bearzi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/yohann_bearzi/32/671_2.png) [@Yohann\_Bearzi](https://discourse.vtk.org/u/Yohann_Bearzi)\
**Post date:** [December 19, 2023, 3:42pm UTC](https://discourse.vtk.org/t/vtkimagedifference-does-not-detect-different-images/12935/2 "2023-12-19T15:42:09Z")

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It is a known issue. We are currently in the process of changing the metric used for image comparison in regression testing (see [here](https://discourse.vtk.org/t/enhancing-vtks-image-testing-framework-a-transition-to-ssim-and-lab-channels/12584)). This will be quite impactful for VTK and projects depending on it so it will be opt in at first. The current metric is too forgiving and does not capture enough information in the image to be satisfactory.

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_[View the full topic](https://discourse.vtk.org/t/vtkimagedifference-does-not-detect-different-images/12935)._