If you're of a historical mindset, and you're going back in time to check out some of the games that started the entire console gaming revolution, you may be getting mis-information from emulated Atari 2600 titles. While the programming and graphics from Atari games may be spot-on, one thing emulators don't take into account is the way old-school 70s and 80s televisions interacted with games...until now.
Atari games weren't played on the crisp, digital screens we know today. Instead, the games were played on CRT televisions, with all the interference, fuzziness and non-digital dirt that they brought with them. In testament to the ingenuity of old-school programmers, Atari's best artists turned the TV's shortcomings into advantages. Take a look at the comparison screenshot above to see what I mean. The left, digital half is vastly different than the right half. Note how the car on the right looks much better blurred than the car at left.
Atari programmers used the after-image burned into gamers' eyes to "flicker" objects between frames. They also took advantage of the "texture" created by analog TVs, and they took into account the fuzziness created by TV's analog style to create art that looked a little "softer" than it does perfectly rendered in digital form. Another difference between old and new school gaming is noise. While an area of your screen will show static color in digital form, on an old television, noise is added, and the image contains variations.
In the end, what you see when you use an emulator like Stella is not what you would have seen back in 1978. But programmers at Georgia Tech have tackled the problem and created a way to make your computer monitor behave like a TV to really bring up the realism.
The Georgia programmer are working with the maintainer of the free, open-source Stella emulator to add the effects as an option. If it works out, project head Ian Bogost hopes to add the effects to other emulators, so everyone can enjoy pitch-perfect old timey emulation.