I'm confused. Does this just act as a wrapper around the php function imagejpg? It looks like the compress function just, makes sure the file names are set up

I'm confused. Does this just act as a wrapper around the php function imagejpg? It looks like the compress function just, makes sure the file names are set up ok, and then uses the built in function imagejpeg (and also deletes the copy of the image that was passed as an argument I guess? I didn't read it closely.) I think I'm likely missing something