Hello,
I’m trying to visualize a section of a 3D scan along with a 3D multi-class segmentation mask. I want to keep the scan in grayscale and, at the same time, to use distinct colors for the different classes in the mask.
Currently, the scan and the mask are loaded as groups of PNG images. Then, I’m using Coloring -> PNGImage for both. It seems that if I change the color preset for one component, it is also being changed for another.
Is there a way to overcome this limitation?
Not sure if I understand fully. However, when you have issues like this, you can use the calculator filter to create a variable that represents what you actually want to paint. Would that work?
Assuming that you have loaded two different PNG files (and it sounds like you have), then you can click the Use Separate Color Map button 
to select a different color map to each object in the pipeline browser.
Thank you, that is exactly I was looking for! Both of your approaches work just fine.
For the info, Use Separate Color Map is not implemented in ParaView 5.4.1, which is distributed via the Ubuntu repos. Anyway, it is available in 5.6.0.