LRGB combination hangup

[jamesRC]

Hello, people;

I have 3 images on the screen, I'll call them GrayImage1, GrayImage2 and GrayImage3
I can't combine these into RGB because of the error message "process can only be
applied to RGB color images".

If I convert them to RGB and try again with these images on the screen,
I get "no compatible images" in the box that selects R, G and B channels.

What might cause this, please?

James

[pfile]

when you apply a process with the square box button, you apply it to an image (it is square to mean that it applies the process to an image window). thus you're asking ChannelCombination to merge the 3 images identified in the UI into one of those 3 greyscale images (whichever one is frontmost) and it's failing because the target has to be RGB.

then when you changed your 3 input images to RGB, ChannelCombination failed because it requires 1-channel input images.

what you need to do is use the round "apply global" button. for processes that support it, by clicking this you're saying "don't apply this to any particular image - run in the 'global' context". in this case, ChannelCombination creates a new RGB image and then assigns the channels from the 3 input images in the UI.

a much slower alternative to this is to create a new RGB image of the right pixel dimensions and then use the square button to apply the ChannelCombination process to that new image. but that would be a PITA

rob

[jamesRC]

Rob,

Aha, a bit of an beginner-ish slipup? 
Thank you very much for making it so clear. I'll get right to it.

James

[pfile]

no big deal, it is a subtlety of the PI UI...