A full quarter has passed since R600 showed up, which means it's a full quarter since we promised this piece. Heck, RV610 and RV630 had a chance to finally show up, too, which definitely means we're overdue! The hold up? What we wanted with the IQ analysis was to say something extra, on top of the standard stuff presented in the launch day analysis for R600.
In that piece we covered things like apparent AF quality using the standard tools, and said the standard things. We took a look at AA quality as normal by poking grids and bare triangles, and we commented on the down-filter properties and apparent IQ issues in games. So did everyone else, though. Thus, when preparing for this piece we wanted to go a bit further, in order to say something worthwhile and not just regurgitate what we'd said in the initial analysis. Why wait a month or more for that.
And while we shouldn't make excuses for tardy behaviour, since that's nobody's fault but ours, that process of saying something new has been a struggle, but a struggle we thought we should have. We've been developing new in-motion and static IQ tests, testing driver revisions, and poking performance limits of the architecture when generating good looking pixels. We've also been wondering how best to talk about the AA quality over and above what was initially said, and it's been a struggle to pin things down there, both talking to AMD and working with folks elsewhere.
In short, we thought our IQ analysis could do with a kick up the ass, and we wanted to do that, but it's been a labourious and grief-laden thing to take a shot at. So what follows is our look at AMD R6-series image quality as it stands, and it's one that focuses on the AA down-filter more than anything else. It's where AMD have changed the game the most, introducing forward-looking custom filters, so the focus is an obvious one.
We spent some time back in July creating a filter harness to test pluggable filters for MSAA, which drove us to write a separate paper just on the AA down-filter, which we'll drape the rest of this article around, using it as a focus. So you can think of this as the initial lacing of the boots that'll do the kicking, so when the kick comes when we're finally done on the software side, it should be a hefty one.
First, a quick (we promise) look at the basics of AF and AA quality as seen before, to refresh your memory. Those things happen in the sampler, ROP and shader core hardware shown in the linked overview diagram, so ignore the front end of the chip for the time being and let's take a look at what the final pixel-level output is like.