# Convert nrrd to nii.gz

**URL:** <https://discourse.slicer.org/t/convert-nrrd-to-nii-gz/16694>\
**Category:** Support\
**Tags:** nifti, nrrd, conversion\
**Created:** [March 22, 2021, 3:02pm UTC](https://discourse.slicer.org/t/convert-nrrd-to-nii-gz/16694 "2021-03-22T15:02:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Hball99](https://avatars.discourse-cdn.com/v4/letter/h/7cd45c/32.png) [@Hball99](https://discourse.slicer.org/u/Hball99)\
**Post date:** [March 22, 2021, 3:02pm UTC](https://discourse.slicer.org/t/convert-nrrd-to-nii-gz/16694/1 "2021-03-22T15:02:26Z")

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Hello there!

For a special use case, I need all my data in nii.gz format. Right now, I have 200+ CT-Volumes plus segmentations both stores in .nrrd data format. I could open each of those volumes/segmentations in 3D slicer manually and store them as nii.gz, but I am looking for a way to script that problem, so I don’t have to do it 200 times.

Since I am a newbie to that topic, I do not know where to start and I was wondering if you have any good ideas/known libraries/ways to script that problem within 3D slicer or outside 3D slicer.

Thanks in advance!

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [March 22, 2021, 4:07pm UTC](https://discourse.slicer.org/t/convert-nrrd-to-nii-gz/16694/2 "2021-03-22T16:07:37Z")

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These scripts were written for diffusion images but should work for other volumes.

> **[pnlbwh/conversion](https://github.com/pnlbwh/conversion)**
>
> Various mri conversion/modification scripts. Contribute to pnlbwh/conversion development by creating an account on GitHub.

dcm2niix should also work.

> **[rordenlab/dcm2niix](https://github.com/rordenlab/dcm2niix)**
>
> dcm2nii DICOM to NIfTI converter: compiled versions available from NITRC

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<div class="post-metadata">

**Author:** ![dave3d](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dave3d/32/5003_2.png) [@dave3d](https://discourse.slicer.org/u/dave3d)\
**Post date:** [March 22, 2021, 8:32pm UTC](https://discourse.slicer.org/t/convert-nrrd-to-nii-gz/16694/3 "2021-03-22T20:32:28Z")

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Really easy to do in Python with SimpleITK.

```
import SimpleITK as sitk

img = sitk.ReadImage("your_image.nrrd")
sitk.WriteImage(img, "your_image.nii.gz")

```

fin