On Mon, Jun 21, 2021 at 04:31:45PM -0500, Bill Gee wrote:
Now I need to figure out how to set transparency on each layer.
Bring up the Gimp "Layers" dialog (shortcut key is Ctrl+L) and you can click on each layer and drag the "Opacity" slider to make them partly transparent. Or you can change the mode on each layer to "Darken only" and the result will be the darkest part of any layer, which is probably what you're after (assuming your sketches are dark lines on a white background).
I wonder if Bruce's faint memory about setting transparency with an external editor worked because of using PNG format? My own faint memory is that xTherion uses different libraries to handle png and jpg files. Handling of transparency is probably a feature of the image library rather than xTherion.
I don't think the standard JPEG format supports transparency. Cheers, Olly