# How to export voxel intensity

**URL:** <https://discourse.slicer.org/t/how-to-export-voxel-intensity/951>\
**Category:** Support\
**Created:** [August 26, 2017, 2:49am UTC](https://discourse.slicer.org/t/how-to-export-voxel-intensity/951 "2017-08-26T02:49:12Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**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:** [August 26, 2017, 4:26am UTC](https://discourse.slicer.org/t/how-to-export-voxel-intensity/951/4 "2017-08-26T04:26:08Z")

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Probably the simplest would be to get the volume as a numpy array and then write out the voxel indices and values you are interested in. Something like this (this outputs all voxels that has value \>260):

```
import numpy as np
voxelArray = slicer.util.arrayFromVolume(getNode('MRHead'))
indices = np.where(voxelArray>260)
numberOfVoxels = len(indices[0])
for pointIndex in range(numberOfVoxels):
  i = indices[0][pointIndex]
  j = indices[1][pointIndex]
  k = indices[2][pointIndex]
  print("%d %d %d %d" % (i, j, k, voxelArray[i,j,k]))
```

See some more examples in the script repository: [https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Modify\_voxels\_in\_a\_volume](https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Modify_voxels_in_a_volume)

If you need physical (RAS) coordinates instead of voxel coordinates (IJK) then you have to multiply the (x,y,z,1) vector from the left with the volume’s IJKToRAS matrix.

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