Blu ray played on pc, is 2k resolution anti-aliased to 1080p?

I read on wikipedia that anti-aliasing is when a higher resolution is fit to a smaller resolution.

The video card frame buffer/ ram, needs to be enough so the videocard can do anti-aliasing properly.

This frame buffer/ram, isn't so important in pcie 2.0 or 2.1, but in pcie 1.0 16x the frame buffer on the video card is the only ram available, it holds the video frame and enables things ike anti-aliasing to be done to the frame.

In pcie 1.0 16x if you have a 2k source frame being anti-aliased to 1080p and you don't have enough video card ram to do this properly you will have anti-aliasing issues.

So my question is, is blu ray 2k on the disk, or do they anti alias it at the factory to 1080p?

I use ati overscan slidebar in the catalyst settings for my lcd tv.
This makes the picture bigger so it fill my tv screen.
I want to know if this changes the way the uvd handles the resolution.

Since the size of the screen is being changed by the "scaling options" slide bar then does this also affect how the ati uvd treats the resolution so it may need to have anti-aliasing for some technical reason I can't think of right now?

I found the answer to my question in post #5. If I don't use the ati catalyst "scaling options" to make the picture fill the screen but leave it at default I get no aliasing when I play the blu ray movie Rambo at 6 minutes and 8 minutes.

6 minutes into the movie I see him get off the boat and if I look at the wooded deck I see aliasing or not.
8 minutes into the movie the shot goes from Rambo to the preachers and there is aliasing on the mans face or not.

I have 256MB on my ati 2600xt pcie 1.0 16x videocard.
It looks like scaling the picture to fill the screen increases the resolution past 1080p and the picture needs to be anti aliased when playing a blu ray movie, so if you don't have enough ram you will see aliasing like I have which goes away if you don't scale the screen.