# \-/+ 3 sigma normalization
**URL:** https://discourse.slicer.org/t/3-sigma-normalization/28947
**Category:** Support
**Tags:** normalisation
**Created:** [April 16, 2023, 11:46pm UTC](https://discourse.slicer.org/t/3-sigma-normalization/28947 "2023-04-16T23:46:55Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@mahmood](https://discourse.slicer.org/u/mahmood)
#### Post date: [April 16, 2023, 11:46pm UTC](https://discourse.slicer.org/t/3-sigma-normalization/28947/1 "2023-04-16T23:46:55Z")
sorry
I have a question. How can I apply -/+3 sigma normalization on my dicom files?
Thanks
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### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [April 16, 2023, 11:57pm UTC](https://discourse.slicer.org/t/3-sigma-normalization/28947/2 "2023-04-16T23:57:33Z")
When Slicer loads an image and window/level then uses +/- 3 sigma normalization by default for displaying the image (sets window/level so that 0.1 to 99.9% of the voxel intensities are mapped to the displayed intensity range).
In DICOM files very often the window/level is already specified and then that is used. If that is not what you want then you can right-click on the image and choose `Window/Level presets` → `Automatic`.
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### Author:  [@Radiologist00](https://discourse.slicer.org/u/Radiologist00)
#### Post date: [June 11, 2023, 6:27am UTC](https://discourse.slicer.org/t/3-sigma-normalization/28947/3 "2023-06-11T06:27:09Z")
Hi,
Can I then assume that my images go through -/+ 3 sigma normalization by default?
How about the choice “normalize image filter”?
Best wishes,
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### Author:  [@Saima](https://discourse.slicer.org/u/Saima)
#### Post date: [July 25, 2023, 5:54am UTC](https://discourse.slicer.org/t/3-sigma-normalization/28947/4 "2023-07-25T05:54:51Z")
Hi andras,
I want to normalise APTw image with range [-5, 5]. How can I do this?
regards,
Saima