I have an image where I know the distance between two points in meters (say 800).
How do I import this image in QGIS (3.8) so that I get this distance when I measure with the tool in the toolbar?
Note: The image shows just a small part of the planet, so there is no distortion to speak of. So unlike other questions, I'm not trying to map a whole planet. If this matters, the planet has the size of Earth.