# Is WarpImageFilter supposed to reverse a displacement field?

**URL:** https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819
**Category:** Beginner Questions
**Tags:** itk, warp, python
**Created:** [March 22, 2023, 2:32pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819 "2023-03-22T14:32:33Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![edgar](https://discourse.itk.org/letter_avatar_proxy/v4/letter/e/b487fb/32.png) [@edgar](https://discourse.itk.org/u/edgar)
#### Post date: [March 22, 2023, 2:32pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819/1 "2023-03-22T14:32:33Z")

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Continuing the discussion from [How to create a displacement field image from a numpy array without files?](https://discourse.itk.org/t/how-to-create-a-displacement-field-image-from-a-numpy-array-without-files/5717/2):

# Is WarpImageFilter supposed to reverse a displacement field?

Hi! I just figured how to [warp an image with a displacement field](https://discourse.itk.org/t/how-to-create-a-displacement-field-image-from-a-numpy-array-without-files/5717), but I think that I am doing it backwards… or is `WarpImageFilter` supposed to reverse the displacement field?

In the figures below, the red block is moved -1 in x, y and z, but the displacement field was 1 in each direction.

 ![itk_warping_inverts_displacement_1](https://discourse.itk.org/uploads/default/original/2X/7/799493d5ba4282ff26e4c5bf653777ac8eb9ff4e.png)  
 ![itk_warping_inverts_displacement_2](https://discourse.itk.org/uploads/default/original/2X/7/73af4634c77587de6198628fefd0cd37e684e976.png)

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### Author: ![zivy](https://discourse.itk.org/user_avatar/discourse.itk.org/zivy/32/1726_2.png) [@zivy](https://discourse.itk.org/u/zivy)
#### Post date: [March 22, 2023, 2:53pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819/2 "2023-03-22T14:53:12Z")

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Hello @edgar,

[This discussion](https://discourse.itk.org/t/demons-displacement-field-backwards/1598) answers your question.

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### Author: ![blowekamp](https://discourse.itk.org/user_avatar/discourse.itk.org/blowekamp/32/79_2.png) [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [March 22, 2023, 2:56pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819/3 "2023-03-22T14:56:51Z")

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Also the general `ResampleImageFilter` should be preferred over the specialized `WarpImageFilter`.

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### Author: ![edgar](https://discourse.itk.org/letter_avatar_proxy/v4/letter/e/b487fb/32.png) [@edgar](https://discourse.itk.org/u/edgar)
#### Post date: [March 22, 2023, 3:13pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819/4 "2023-03-22T15:13:30Z")

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Yes, it does. Thank you very much. Sorry for the duplicate posting.

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### Author: ![edgar](https://discourse.itk.org/letter_avatar_proxy/v4/letter/e/b487fb/32.png) [@edgar](https://discourse.itk.org/u/edgar)
#### Post date: [March 22, 2023, 3:14pm UTC](https://discourse.itk.org/t/is-warpimagefilter-supposed-to-reverse-a-displacement-field/5819/5 "2023-03-22T15:14:14Z")

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Thanks, I will look into that (when I have to cross that bridge again q: ).