v005: Apparently bash does not do tilde expansion nor $HOME expansion within [[ ... ]].
So I had to implement it myself.
There is probably an easier way than mine to do this.
Let me know if you find one.

Anyhow, applying a color scheme from an image now works if you use a full path to the image or any of the formats:

~/Images/tigermonk.jpg
~xaos52/Images/tigermonk.jpg
$HOME/Images/tigermonk.jpg