The MiSTer team has just implemented an “adaptive” transparency blending technique for the Sega Genesis and Sega CD cores. In some cases, this is an improvement over the previous composite blending technique, as it tries to detect the layer that would benefit from the blending and blur only that layer.
For those unfamiliar, developers in the CRT-era would often create artwork in games to take advantage of composite video’s blurry interference. One of the most famous examples is the waterfall in Sonic The Hedgehog, but I actually think the clouds in Crusader Of Centy might be an even better example (click on all pictures for a full-sized view).
When viewing games in RGB that were designed with composite blur in mind – regardless if you’re using a CRT or flat-panel – transparent assets in a game end up just looking like dots. The previous blurring technique used in the MiSTer as well as the Analogue Sg would blur the entire screen, trying to re-produce this effect. This would create the desired look for the dithered assets, but also blur parts of the screen that were just normal artwork.
This new “adaptive” blending has made it so that (in most cases), only the assets that use dithering are blurred and everything else stays sharp! This is a truly impressive accomplishment and I hope someday other consoles can benefit from it:
Other games like Virtua Racing rely so heavily on the dithering effect, it might be impossible to only blur things like the fence, tires, shadow under the car, etc:
Unfortunately, the same goes for FMV Sega CD games as well. Those haven’t aged well overall though and while it would be nice to blur the screen, but keep the controls sharp, maybe the best way to experience them is just in composite video on a CRT?
I think one scenario in which the blurring effect would really benefit the experience is with NES and SMS 3D games (and that one SNES game ;p). Much like with dither blending, the 3D effect in most of those games doesn’t look as good in RGB and especially on larger displays. Games that truly used the 3D effect as part of the game like Maze Hunter still look really impressive, including with the beta MiSTer core that outputs 3D to a modern 3D flat panel TV!
Unfortunately, most other games seemed to offer the 3D effect added as a bit of a gimmick. I still think it’s a really fun thing to experience on a 20″ or smaller CRT, however I’d love to see both the composite blurring and 3D core features added to the main MiSTer SMS core! Fingers crossed the team feels the same way!
