Thanks to everyone in this thread, especially you Darren, who had a VI on your shelf showing that I should just have done what Yair suggested .
I've basically reworked Darren's VI, into one that creates a 100% correct conpane image. Here's the FP illustrating an example (the VI itself is attached this post if you can use it):
So that's probably the fastest way in G to get the conpane image. I discovered a funny thing while coding this; the Get Image method of the SubVI class returns slightly wrong terminal colors for the conpane image!
For instance "Boolean green" is RGB 0,127,0 in the BD, but the image when extracted with the Get Image method contains a slightly darker green color, namely 0,102,0 instead. So an unexpected side effect by this small exercise were even more correct conpane images .
Cheers,
Steen
GetConpaneImage.vi