Unable to split a generated multi-channel image unless it is first saved then re-loaded into ImageJ


I am using the Trainable Weka Segmentation 3D plugin to generate a 2-channel probability map. The (minor) issue is that I am not able to split the channels of the resulting map (using Image -> Color -> Split Channels) unless the map is first saved and then re-loaded into ImageJ. The error states “multichannel image required”. Is this a bug? I made sure that the image is active and that no other images are open in ImageJ.

I have tried this both in ImageJ 1.52p and 1.52s

Also note that this issue occurs with probability maps generated with Labkit as well, so it may not be plugin-specific.

Here is a screenshot of the image properties:


Instead of saving and reloading you can convert the image into a composite:
Image > Color > Make Composite
Then you are able to split the channel via Split Channels.

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This is because the resultant probability maps are a stack rather than a multi-channel image.

What @schmiedc will work but an alternative if you want them in be separate windows than you can go to Image > Stacks > Stack to Images.