# What is different HU and voxel value

**URL:** <https://discourse.slicer.org/t/what-is-different-hu-and-voxel-value/7213>\
**Category:** Support\
**Created:** [June 18, 2019, 2:36am UTC](https://discourse.slicer.org/t/what-is-different-hu-and-voxel-value/7213 "2019-06-18T02:36:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kscript](https://avatars.discourse-cdn.com/v4/letter/k/ec9cab/32.png) [@kscript](https://discourse.slicer.org/u/kscript)\
**Post date:** [June 18, 2019, 2:36am UTC](https://discourse.slicer.org/t/what-is-different-hu-and-voxel-value/7213/1 "2019-06-18T02:36:20Z")

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HI.

**1.** I open dicom file’s header using 3D Slicer. i can get LargestImagePixelValue and smallestImagePixelValue.  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/b/1bd9f5d5363cd879e9c3c319b08c8be6d2e98325.png)

**2.** And I check Volumes’ Histogram using 3D Slicer. and I check HU(HounsField Unit) Range.  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/4/d/4d1027dbce7c16cbabd3d3a063e65aba98ff054d.png)

but Two results are different.  
pixel value range(first works result) is 0~4095. but HU(HounsField Unit) Range(Second works result) is -1410~3505

So I’m curious. Why Results are different.  
Can i convert HU to pixel value??

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<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [June 18, 2019, 3:17am UTC](https://discourse.slicer.org/t/what-is-different-hu-and-voxel-value/7213/2 "2019-06-18T03:17:55Z")

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Rescale slope and intercept values are used to compute displayed values (in HU) from raw pixel values.