# Sitk composite image
**URL:** https://discourse.itk.org/t/sitk-composite-image/2514
**Category:** Beginner Questions
**Tags:** simpleitk
**Created:** [December 12, 2019, 4:02am UTC](https://discourse.itk.org/t/sitk-composite-image/2514 "2019-12-12T04:02:34Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@kayarre](https://discourse.itk.org/u/kayarre)
#### Post date: [December 12, 2019, 4:02am UTC](https://discourse.itk.org/t/sitk-composite-image/2514/1 "2019-12-12T04:02:34Z")
How can one write a composite image to png with sitk?
Currently I cast a composite image with three components to vectorUint8, but when I try to write it to file it gives and itk error. Any suggestions or alternatives?
---
### Author:  [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [December 12, 2019, 3:29pm UTC](https://discourse.itk.org/t/sitk-composite-image/2514/2 "2019-12-12T15:29:59Z")
Hello,
The following works for me:
```auto
sitk.WriteImage(sitk.Image([10,10], sitk.sitkVectorUInt8, 3), "foo.png")
```
Please describe in detail what you are going, provide minimal reproducible code, and include the error message received. The work needed to reduce your problem to a minimal example frequently revels a bug in the code, and produced a shareable example for other to help with otherwise.
---
### Author:  [@kayarre](https://discourse.itk.org/u/kayarre)
#### Post date: [December 12, 2019, 5:38pm UTC](https://discourse.itk.org/t/sitk-composite-image/2514/3 "2019-12-12T17:38:44Z")
Thank you @blowekamp. I need to pull out the essential part from the tangle and will post some code. I think maybe the issue could be related to `, 3)` but I will investigate and reply with a minimal example.
---
### Author:  [@kayarre](https://discourse.itk.org/u/kayarre)
#### Post date: [December 12, 2019, 7:05pm UTC](https://discourse.itk.org/t/sitk-composite-image/2514/5 "2019-12-12T19:05:40Z")
I compared the image you showed and the image I am trying to save and look identical except for the size of the image.
The issue was that the folder I want to write to wasn’t there, but the error was cryptic which makes sense now.
```auto
Traceback (most recent call last):
File "create_stack.py", line 112, in
main()
File "create_stack.py", line 108, in main
writer.Execute(new_image)
File "/Users/sansomk/anaconda3/envs/reg/lib/python3.7/site-packages/SimpleITK-1.2.0rc2.dev1162+g2a79d-py3.7-macosx-10.7-x86_64.egg/SimpleITK/SimpleITK.py", line 6808, in Execute
return _SimpleITK.ImageFileWriter_Execute(self, *args)
RuntimeError: Exception thrown in SimpleITK ImageFileWriter_Execute: /Users/sansomk/build/simpleelastix/build/ITK/Modules/IO/PNG/src/itkPNGImageIO.cxx:543:
Problem while opening the file.
```