# Runtime Error trying to use the LabelMapToBinaryImageFilter in SimpleITK

**URL:** https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828
**Category:** Beginner Questions
**Tags:** python, simpleitk
**Created:** [April 6, 2018, 12:27am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828 "2018-04-06T00:27:14Z")
**Posts on this page:** 5
**Page:** 1

<div class="post-metadata">

### Author: ![Diego\_C](https://discourse.itk.org/user_avatar/discourse.itk.org/diego_c/32/279_2.png) [@Diego\_C](https://discourse.itk.org/u/Diego_C)
#### Post date: [April 6, 2018, 12:27am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828/1 "2018-04-06T00:27:14Z")

</div>

Hello,

I am trying to combine multiple images (same spacing, dimensions, etc.) Each image contains a 1 for object and 0 for background and these are 3D volumes.

this is my code:

```auto
def labels_to_binary_image(image_list):
    """Creates a new image that contains all the labels"""
    arr_union = None
    for image in image_list:
        if arr_union is None:
            arr_union = sitk.GetArrayFromImage(image)
        else:
            arr_union += sitk.GetArrayFromImage(image)

    ima_union = sitk.GetImageFromArray(arr_union)
    _filter = sitk.LabelMapToBinaryImageFilter()
    return _filter.Execute(ima_union)
```

When I run it I obtain this error:

```auto
  File "/Users/odin/anaconda/lib/python2.7/site-packages/SimpleITK/SimpleITK.py", line 41239, in Execute
    return _SimpleITK.LabelMapToBinaryImageFilter_Execute(self, *args)
RuntimeError: Exception thrown in SimpleITK LabelMapToBinaryImageFilter_Execute: /scratch/dashboards/SimpleITK-OSX10.6-intel-pkg/SimpleITK/Code/Common/include/sitkMemberFunctionFactory.hxx:196:
sitk::ERROR: Pixel type: 8-bit unsigned integer is not supported in 3D byN3itk6simple27LabelMapToBinaryImageFilterE
```

What am I doing wrong?

Thanks,

Diego

---

<div class="post-metadata">

### Author: ![Diego\_C](https://discourse.itk.org/user_avatar/discourse.itk.org/diego_c/32/279_2.png) [@Diego\_C](https://discourse.itk.org/u/Diego_C)
#### Post date: [April 6, 2018, 12:38am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828/2 "2018-04-06T00:38:52Z")

</div>

This is what intended:

```auto
def labels_to_binary_image(image_list):
    """Creates a new image with the union"""
    arr_union = None
    for image in image_list:
        if arr_union is None:
            arr_union = sitk.GetArrayFromImage(image)
        else:
            arr_union += sitk.GetArrayFromImage(image)

    arr_union[list(np.where(arr_union > 0))] = 1 # just make it binary again

    #ima_union = sitk.GetImageFromArray(arr_union)
    #_filter = sitk.LabelMapToBinaryImageFilter()
    #return _filter.Execute(ima_union)

    ima_union = sitk.GetImageFromArray(arr_union)
    return ima_union # this works!
```

---

<div class="post-metadata">

### Author: ![blowekamp](https://discourse.itk.org/user_avatar/discourse.itk.org/blowekamp/32/79_2.png) [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [April 6, 2018, 12:49am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828/3 "2018-04-06T00:49:00Z")

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With your implementation you loose the image meta data! You should stay in SimpleITK and just use the overloaded operators. This one liner may work too:

‘’’

sitk.NaryAdd(image\_list)!=0

‘’’

You probable could do ’sum(image\_list)’ too

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<div class="post-metadata">

### Author: ![Diego\_C](https://discourse.itk.org/user_avatar/discourse.itk.org/diego_c/32/279_2.png) [@Diego\_C](https://discourse.itk.org/u/Diego_C)
#### Post date: [April 6, 2018, 12:52am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828/4 "2018-04-06T00:52:44Z")

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Hi Bradley, I think your post got cut off…

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<div class="post-metadata">

### Author: ![blowekamp](https://discourse.itk.org/user_avatar/discourse.itk.org/blowekamp/32/79_2.png) [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [April 6, 2018, 1:02am UTC](https://discourse.itk.org/t/runtime-error-trying-to-use-the-labelmaptobinaryimagefilter-in-simpleitk/828/5 "2018-04-06T01:02:15Z")

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I removed the extra bit at the end. The proper SimpleITK solution really is that short.