With the series firmly in the 500 episode range, it's definitely showing its overall appeal in Japan. But if you're getting into the series, it can be difficult unless you've got a lot of the episodes available locally for rental or someone you know has a lot of it. Well, let the broadcasters help out as the series is getting shown again on TV with some mild remastering going on to help clean up the elements which are a bit rough and raw when you get down to it compared to the newer episodes. The series was shot on film originally so it definitely had its share of visual defects.
To be clear, it doesn't look like it's getting a Dragon Ball Z Kai kind of remaster where they're re-editing it and re-animating parts of it. It's simply being cleaned up and shown again. This new broadcast gives older fans a chance to re-experience the early episodes again and to hopefully draw in new viewers.