How can overlapping raster map sheets be overlaid in QGIS, and manually blended together in GIMP?
I have an overlapping set of hand-drawn raster maps that contain varying levels of detail and would would like to combine these into a single large map using QGIS and GIMP. Since the information in the overlap regions is sometimes complementary, I would like to be able to choose manually which pixels to take from which map sheet.
I was successful at georeferencing them onto OpenStreetMaps, and would now like to blend the overlaps together (which I cannot seem to work out how to do in QGIS). In GIMP, using one layer for each map of a given two map sheets, I can delete the bits in the top layer which I want to use from the lower one, make these regions transparent using a layer mask, and then merge down.
How do I transfer my aligned map sheets as individual layers into GIMP for editing and then back to QGIS?
I am new to QGIS and have played around with this for a while now but can't quite figure it out. Maybe I'm overlooking something or I am on the wrong track altogether.