Yeah, with quality footage that's low noise, resampling / resizing from one very large res image to another one is far less destructive to the image itself than the same process for lower res. If people keep mentioning you need to be a certain distance to perceive all the benefits of whatever res your movie is at, vs your screen size, that applies way more to this resampling business. There is no 1:1 in the end. Every single pixel is processed a bunch of times before arriving at your eyes, and I think image algorithms are quite good enough now. I mean, We do this filtering in videogames when we have a 2k x 2k texture ALL the time, because it NEVER ends up on your screen in a 1:1 ratio, i.e. it's skinned on polygonal meshes and run through about a dozen algorithms from shading to postprocessing to gamma correction, before even hitting the frame buffer of your video card, let alone getting out from there to your screen to your eyes. I agree that less processing is sometimes better, but often-times not. Queue Darby. People like image processing, in the same sense that they like subtly distorted sound.
My point is 4K res over 2K res is >>> far more important than having to scale out those pixels before final 2160p mastering. I just simply don't buy the argument that it makes it very blurry at all. Upsizing is a different story, but we're talking about merely changing the aspect ratio by a tiny bit here. I'd very much like to see some objective measurements on 4K -> 2160p resampled test patterns as to how much perceivable "blurriness" is introduced by the best image algorithms. Maybe on certain patterns, sure, like fences being panned you might see some waves going through (like we do in videogames...alpha blending textures with repeated patterns are notorious for introducing artifacts, but even these are being solved in real time now...I simply don't think at the mastering level they would be so tough for someone to fix in postproduction / mastering)
I watch computer and video content at 1:1 almost every day on a 24" 1920x1200 LCD monitor via DVI or HDMI. Looks luvly. I like the nice crisp, clear, unblurrified pixels. I'm sure you do the same when you're designing stuff on your PC. Why try to deny HDTV or UHDTV viewers the same pleasure?
If you own a 1080p display that's capable of true 1:1 mapping, then you can get an idea how scaling to a slightly different resolution will impact the fine detail in images by simply switching the display from 1:1 into OVERSCAN mode. The Overscan mode will scale the image to a slightly larger size (and also crop off the edges). The effect is similar to scaling 4K to 2160p, or 2K to 1080p, except that the image is being scaled slightly smaller in these cases, rather than larger... The results are much the same though. And much of the fine detail will go out the window on a 1080p display if you turn on Overscan, due to the scaling/resampling of the picture.
I realize that not all TVs are capable of true 1:1 mapping, and some are also capable of scaling on a sub-pixel level (which is a different type of operation). But if you want to see the full untarnished detail in a still or video image without alteration, then you should set the display to 1:1. That's what is generally recommended here anyway (for good reason imho).
Edited by ADU - 5/10/13 at 6:11pm