I'm in the process of georeferencing some old black and white aerial pictures from 1990 in QGIS 2.4. So far, this is business as usual, no problems.
Of course I get the usual black triangles, because I'm reprojecting them to EPSG:25833. So I checked "use 0 for transparency when needed". But now my georeferenced pictures are spotted with occasional transparent pixels, because of course there are legitimate black pixels all over my old aerial pictures.
How do I avoid this? Is there any workaround available? Maybe change the no-data color value to some better value? And most important, how can I do this for ~50 files as economically as possible?