08-23-2023, 08:38 PM
(08-23-2023, 08:01 PM)dscriven Wrote: Thanks for your input - it led me to a solution.
It seems that a condition for the transfer of transparency (copying the alpha channel) is that the destination has to be transparent. I was able to correctly copy the images if I cut holes in the background of the montage of the appropriate size revealing the transparent underlayer and then used Edit->Paste into Selection. I didn't need to add a mask to the original image - a simple copy did the trick.
If I'm right about this condition, shouldn't there be a note about it somewhere? I wasted many hours yesterday and today over this (to me, surprising) problem.
The copy is transparent. If you copy to a new layer, you will see that this layer has transparent pixels where the source has transparent pixels.
But a transparent pixel over a non-transparent background pixel results into a non-transparent pixel. This is Rule One of layer composition in all image editors. Otherwise erasing a bit of a top layer would make everything under it transparent too... In the physical world, when you stack sheets of glass or tracing paper, the result is at least as opaque as the more opaque sheet, not as transparent as the more transparent sheet.