# How to get a pointer of a VTK image to use in C.

**URL:** https://discourse.vtk.org/t/how-to-get-a-pointer-of-a-vtk-image-to-use-in-c/6406
**Category:** Support
**Created:** [August 17, 2021, 9:13pm UTC](https://discourse.vtk.org/t/how-to-get-a-pointer-of-a-vtk-image-to-use-in-c/6406 "2021-08-17T21:13:37Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Luis\_Carlos\_Carneiro](https://discourse.vtk.org/user_avatar/discourse.vtk.org/luis_carlos_carneiro/32/1360_2.png) [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)
#### Post date: [August 17, 2021, 9:13pm UTC](https://discourse.vtk.org/t/how-to-get-a-pointer-of-a-vtk-image-to-use-in-c/6406/1 "2021-08-17T21:13:37Z")

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Dear All,

```
    vtkSmartPointer<vtkImageConnectivityFilter> connectivity;
    connectivity->SetInputData(image4);
    connectivity->SetScalarRange(255, 255);
    connectivity->SetSeedData(seedData2);
    connectivity->Update();

```

I want to have access to the connectivity image that is in VTK format. How I get the pointer to use the data (image) in C?  
connectivity-\>GetOutput()-\>GetPointData()-\>GetScalars(), do not works. Seems not to be pointer I want.

Thanks,

Luís Gonçalves

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### Author: ![nicfel](https://discourse.vtk.org/user_avatar/discourse.vtk.org/nicfel/32/3639_2.png) [@nicfel](https://discourse.vtk.org/u/nicfel)
#### Post date: [August 18, 2021, 11:05am UTC](https://discourse.vtk.org/t/how-to-get-a-pointer-of-a-vtk-image-to-use-in-c/6406/2 "2021-08-18T11:05:38Z")

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Hello Luis,

u can do the following:

```auto
    vtkSmartPointer<vtkImageConnectivityFilter> connectivity;
    connectivity->SetInputData(image4);
    connectivity->SetScalarRange(255, 255);
    connectivity->SetSeedData(seedData2);
    connectivity->Update();
    vtkSmartPointer<vtkImageData> result = connectivity->GetOutput();
    void* ptr = result ->GetScalarPointer();

```

U can then use it in c but make sure that vtkSmartPointer does not get freed. Otherwise your pointer won’t be valid anymore. I usually do a copy of the data before using it.

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### Author: ![Luis\_Carlos\_Carneiro](https://discourse.vtk.org/user_avatar/discourse.vtk.org/luis_carlos_carneiro/32/1360_2.png) [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)
#### Post date: [August 18, 2021, 12:52pm UTC](https://discourse.vtk.org/t/how-to-get-a-pointer-of-a-vtk-image-to-use-in-c/6406/3 "2021-08-18T12:52:44Z")

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Thanks.