# Error when creating noise map

**URL:** <https://community.mrtrix.org/t/error-when-creating-noise-map/7394>\
**Category:** Uncategorized\
**Created:** [February 25, 2024, 6:26pm UTC](https://community.mrtrix.org/t/error-when-creating-noise-map/7394 "2024-02-25T18:26:17Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Manuela](https://community.mrtrix.org/user_avatar/community.mrtrix.org/manuela/32/4582_2.png) [@Manuela](https://community.mrtrix.org/u/Manuela)\
**Post date:** [February 25, 2024, 6:26pm UTC](https://community.mrtrix.org/t/error-when-creating-noise-map/7394/1 "2024-02-25T18:26:18Z")

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Hello everyone!

I just started using mrtrix. I would like to create a noise map using dwidenoise but when I type the command:

dwidenoise -noise level input.nii.gz noise\_map.nii.gz

I get this error:

dwidenoise: [ERROR] unknown format for image “level” (no file extension specified)  
dwidenoise: [ERROR] error creating image “level”

I imagine it’s a syntax error in the command… how can I fix it?

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**Author:** ![smeisler](https://community.mrtrix.org/user_avatar/community.mrtrix.org/smeisler/32/3620_2.png) [@smeisler](https://community.mrtrix.org/u/smeisler)\
**Post date:** [February 25, 2024, 8:04pm UTC](https://community.mrtrix.org/t/error-when-creating-noise-map/7394/2 "2024-02-25T20:04:29Z")

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Hi @Manuela and welcome to the community!

You must specify an image type by adding a filetype suffix to `level` (e.g. `.nii.gz` or `.mif`).

Best,  
Steven

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**Author:** ![Manuela](https://community.mrtrix.org/user_avatar/community.mrtrix.org/manuela/32/4582_2.png) [@Manuela](https://community.mrtrix.org/u/Manuela)\
**Post date:** [February 25, 2024, 8:30pm UTC](https://community.mrtrix.org/t/error-when-creating-noise-map/7394/3 "2024-02-25T20:30:59Z")

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@smeisler thank you very much! However I am bit surprised because I don’t find a documentation that explains this. For instance here [dwidenoise — MRtrix 3.0 documentation](https://mrtrix.readthedocs.io/en/dev/reference/commands/dwidenoise.html) I don’t find this information. Is this written somewhere ?

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**Author:** ![smeisler](https://community.mrtrix.org/user_avatar/community.mrtrix.org/smeisler/32/3620_2.png) [@smeisler](https://community.mrtrix.org/u/smeisler)\
**Post date:** [February 25, 2024, 8:45pm UTC](https://community.mrtrix.org/t/error-when-creating-noise-map/7394/4 "2024-02-25T20:45:18Z")

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Hi @Manuela,

It is implied by the argument being “The output noise map”, as in the documentation. The error message is also pretty explicit.

Best,  
Steven