[redko]

I'm going to hazard a guess here..might be talking out my butt though .... 2 things...

1. the rest of the layer that you have your RGB40, is it RGB0? and
2. when you merged the layers did you use the "add" option.

I remember reading somewhere here at AAA (don't ask me where) that the best way to merge the layers was to use Gimp as it has the "add" option...I haven't been able to find it myself though :???:

Cheers

Quelty

hum it reminds me something....the topic was how to use gimp to create rivers or nagigable rivers i think.