I've been doing some experiments to see if I can create an effect of shadows on an uneven surface in my stereograms.
Normally I use a black background and the Photo Tool > Select Colors to Enhance feature to select and make the background transparent.
But in this image there was a very dark edge to the beveled letters that was not working. So I added a color that does not appear in the pattern and made that color transparent.
It worked flawlessly.
The attached image has 6 layers with several transparencies.
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