Blur and Bleed: Running Games on a TV

Growing up in the 80's, I was a proud owner of a Commodore 64 and later an Atari ST. They were "home computers" and you hooked them up to your TV, to play games or write code. Nowadays, we all run or computers on large, crisp monitors, at very high resolutions, but those just didn't exist back in the days.

Time passed, technology got more advanced, and before you knew it, you could run all your C64 and Atari ST stuff on your PC, in a window on your desktop. Emulators, great stuff. But you know what? It didn't look anywhere near as nice. The colors where the same, as was the resolution, and all the pixels were obviously in the right place, but you still found yourself thinking "I remember it looking much better".

Don't think it is your mind playing tricks on you. In some ways, things DID look better back in the days. When hooked up to old worn-down TV's with yesteryears technology, usually by means of a coaxial cable, the video output of the old home computers was severely degraded. Today, we wouldn't find that image quality anywhere near acceptable, but back then it was the norm. And the weird thing is, in some ways it made the graphics look better than it really was.

Pixels would be a bit more glowing, and blurry, and bleed into each other, and have a subtle "ghost" effect to them, as some hues would bleed more than others. In addition, there would be slight gaps between pixels, causing what is commonly known as a "scanline" effect. All these things combined to give a sort of illusion of smoother color gradients and softer pixels.

On a modern monitor, like when running under an emulator, you won't get that, which is a real shame. Especially since the art for those old games was hand-pixelled to look good when blurred and bled, as they were created on old CRT screens.

So, I've spent a little time trying to come up with an image filter for my game engine, which will take a pixel image, and make it look more like it would on an old TV screen, by emulating the artefacts we've come to know and love. I've got the concept worked out, and I'm in the process of converting it to a pixel shader, so that it can run fast enough for realtime use. That means that any game using my Pixie game engine will be able to just turn RetroFilter on or off as it please :-)

The main reason I'm developing this is that I want it for the RetroBox project I'm working on (you can read more about this in previous blog entries), as I want to give it that proper oldschool feel to it.