This question already has an answer here:
How can I georeference png images using QGIS, running on OSX?
I've looked at
ExifTool, and the plugins
GeoTag and Import Photos +
Photo2Shape. These tools (and other answers) as far as I can tell all use georeferenced images or images with EXIF data. I would like to load the png somewhere, and drag it around on a basemap from OpenStreeMap to position it where it should be. I know the general location, and just need to position it.
(I think I know the projection, but will find out if that is the case. The images are of an area ~500m x 200m so the projection variation will hopefully not matter hugely if I am incorrect).