When I georeference a map of vegetationtyps (about 20 colours, each representing a certain vegetation) the quality of the georeferenced map is really bad and the some colours has changed (e.g. black becomes white), which makes it almost impossible to recognise the the certain types.
I did the "usuale" procedure: transformation type: linear, method: nearest neighbor. As source I tried jpeg & tiff, same bad result
Any suggestions how to improve the quality of the map and the originality of the map?