Wander the gallery. Look at the art. Be polite. If you feel able please post some great art :)
Matte paintings were used before the dawn of competent computer graphics to simulate a larger/more dramatic/exotic location than can be achieved in a film studio. Paint was directly applied to glass, which then sat between the camera and the actors (leaving a clear section to capture them).
This one is closer to '81 or '82, for Return Of The Jedi.
AFAIK mattes are still A Thing in filmmaking, but they're obviously not done with actual paint on glass.
The best use of CGI is when audiences are wrong about which parts are CGI.
I love these. Corridor Crew on YouTube dives into this stuff and has some great content.
Another example - with the rest of the scene
I've known about matte paintings but I had no idea about the glass part! I just assumed it was composited together somehow. Very cool.
I'm still amazed by how accurate some of the painting is, knowing it would be projected at cinema screen size!
There was a neat trick backlighting the lightsabers frame by frame with a fluorescent tube and a scalpel. Painstaking though.
I would imagine putting it on glass also made it possible to remove the paint easier if a mistake was made, wouldn't it?
Yes probably, you could scrape with a knife or spatula.