I live in Atlanta. 100 miles outside of Atlanta, they don't yet have emmisions testing, but it is rumored to become statewide soon.
Originally, they just shoved a sampling tube into the exhaust and checked the idle CO and HC. That was years ago, in the 70's and 80's. I was a mechanic at the time, and have done quite few of those myself.
Now they put your car on a chassis dyno, and test everything - from CO, HC, NOx, etc. - Under road load and idle conditions. I don't know where you got yours tested, but if they only sampled at idle, it is not legal in the 7 county Atlanta region. You can't get a tag without the computer printout and state authentication.
So, where was this again... I have a few I need tested the OLD way...