Thanks, that all makes a lot of sense.

And you're right, when I close one of my eyes the background doesn't look as complex anymore (and seems softer than I was thinking earlier). Still, though, even with just one eye, the unfocused background seems (or feels) rather likes there's a complex fine-ness to the blur that seems to tell me that things aren't precisely where I'm seeing them on the smallest level. That is statistically true in a quantum mechanical sense, but it feels like my eyes are adding another sort of inaccuracy that sort of feels like Film Grain (albeit much, much higher resolution).

The reason I ask about this is because I was previously looking at how Lowry's grain removal affected some shots in the Sleeping Beauty Blu-ray when slightly-out-of-focus images were a concern. Since then I've just noticed there's a difference between the way depth of vision seems different in a digital image when compared to a film image:

http://www.index-dvd.com/coversbd/screenshots/apocalypto-bd-ss-2.jpg

http://www.dvdbeaver.com/film2/DVDReviews39/the%20counterfeiters%20blu-ray/large/largecounterfeiters%20blu-ray3232.jpg

The latter doesn't feel as flat to my eyes, even though they're both 2D images. It's almost like out-of-focus portions make film grain seem even grainier and for some reason that feels natural and less flat to me. However, I'm an idiot with a lot of things and would like a more knowledgeable opinion correct me if I need it.