ParaView: How to fix "PNGWriter only supports unsigned char and unsigned short inputs"?

Question

I am trying to convert from .vtk to a series of .png slices (i.e., P images each with a resolution of MxN). I am currently using ParaView to attempt to accomplish this. However, upon attempting to save the data as .png, I receive the following error:

vtkkPNGWriter (0x7fa8339b4620) PNGWriter only supports unsigned char and unsigned short inputs

The steps I am currently attempting are:

1. Load the data
2. Apply the filter: Convert from cell to point data
3. Apply the filter: Resample to Image
4. Save Data as .png
5. Error as specified above.

This error appears regardless of data format (i.e., jpg, png, etc.). However, it successfully outputs a .mhd file that is readable with Slicer.

Is there a fix for this, is it just my dataset, or is this a known bug?

I am also open to suggestions for ways of easily generating the sequence of images I need so I can throw them into something like ImageJ. Currently looking at python vtk and SimpleITK.

ParaView Versions Tested:

• Linux 5.4.0
• Windows 5.8.0

question from:https://stackoverflow.com/questions/65909302/paraview-how-to-fix-pngwriter-only-supports-unsigned-char-and-unsigned-short-i

Answer 1

Use a calculator filter to convert your data to unsigned char:

• Load the data
• Apply the filter: Convert from cell to point data
• Apply the filter: Resample to Image
• Add a calculator filter
• Output type : unsigned char
• Formula : yourOwnArray
• Apply
• Save Data as .png