When Is a Pixel Not a Pixel?

These days, “4k” is the buzz of the home theater community. Digital cinema projectors are (slowly) transitioning from 2k resolution to 4k models. Recent Blu-ray titles have been advertised as benefiting from new 4k transfers. Many people assume that the HDTV standard will jump from 1080p to 4k any day now, and a whole new 4k video format better than Blu-ray will be needed to support it. What most people don’t realize is that “4k” isn’t necessarily really 4k. Confused? Read on after the break.

One of the biggest dangers in the home theater hobby today is how easily people can be mislead by specs and marketing hype, which often attempt to reduce complex topics down to simple linear mathematical analogies. High numbers sound better than low numbers. This game is played all the time with stats like contrast ratio. A TV that claims a 100,000:1 contrast ratio must be twice as good as another set that only claims 50,000:1, right? Frankly, no. The issue these specs ignore is just how those contrast numbers are achieved. Is that a native contrast ratio, or is a dynamic iris needed? How are these number measured? Can either of them actually be achieved in real-world viewing? At what point are there diminishing returns? These are just some of the questions that need to be asked.

Likewise, resolution stats have a similar problem. “4k” just sounds so much better than 2K (or 1080p), doesn’t it? Gosh, it must be twice as good! 4 is twice as much as 2. How much more obvious can it be?

Unfortunately, it just doesn’t work that way. In an interview for a publication called Creative Cow (“The Magazine for Media Professionals in Film, Broadcast & Production”), John Galt, the SVP of Advanced Digital Imaging at Panavision, attempts to demystify the difference between real pixels and “marketing pixels.” Here are a couple of relevant quotes from the article, titled “The Truth About 2k, 4k & the Future of Pixels”:

Unfortunately, one of the tragedies of digital imaging, is that now we’ve got these ridiculous numbers games, because so few people understand the fundamentals of the imaging technology, everybody wants a number to latch on to. The numbers don’t mean anything in the context of 100 years of development of film and motion picture technology, optical technology and laboratory practice and cinematographers did wonderful work without understanding anything about the chemistry or photographic emulsion technology.

Whenever I do a presentation about digital imaging, my first question these days is, “Anybody know how many grains of silver are on a frame of film? Hands up, hands up!” Nobody ever puts their hand up. My second question is, “Hands up! Anybody ever thought about this before?” You can tell the nerds in the audience from the hands that go up!

So why do we care? Because after 100 years of being comfortable with a relatively stable film based motion picture technology, along comes this new and disruptive digital imaging technology, and we’re all clutching for some magic number that we can carry around in our heads, and this will define the process for us. Sorry, it doesn’t work that way. It’s messy and it’s complicated, and lots more so today than it was in the days of film.

So if you had true 4K resolution in your local theater, everybody would have to [be] sitting in the first 6 rows. Otherwise they wouldn’t see any extra detail. Their eyes wouldn’t LET them see it. You know this intuitively from passing by these beautiful new monitors at trade shows. You find yourself getting absolutely as close as possible to see the detail, and to see if there are any visible artifacts. At normal viewing distances, you can’t.

So the whole 2K 4K thing is a little bit of a red herring.

The article is pretty technical, but it’s a fascinating read. Galt does a fine job of explaining complex topics in an understandable manner, without simplifying them to the point of abstraction. I recommend it to anyone who’s bought into the hype about 4k, or the hype about any marketing statistics in general.

(Source: Creative Cow)


  1. I am all okay with 4k, at my theater. I think it is CRAZY when people talk about 4k to the home. Most of the people I hear touting it have 37 inch LCDs anyways. I am just not sure what it is they are looking for. No, it seems most people touting 4k at the home have bought cheap, crappy televisions without doing research, brought them home and figured out they did not look as good as they hoped, and instead of admitting they bought a crappy set, they blame the entire HDTV 1080i/p thingy.

    http://pro.sony.com/bbsc/ssr/mkt-digitalcinema/ pretty much tells you where you can really see the improvements with 4k projectors – and the big thing they tout is 2k 3D material. The reason for this, if I remember correctly, is that when you put on those glasses, it cuts the resolution in half. So, simply project the 2k image on a 4k projector, and you get a 2k 3D image.

    Still, though, if my local theater is showing stuff in 2D, and I hear a movie was filmed at 4K, yeah, I would want to see it in 4k.

    That being said, I am not sure where to really go to find out what is in 4k. The sony page I linked to seems to just discuss Sony movies in 4K.

    • I read not too long ago that IMAX was looking at going digital. I remember they were saying that an IMAX film frame had about 18k worth of information in it, so going less than 8k would not be likely. As no projector supported that high of resolution, IMAX was looking at using multiple projectors alligned to pixel perfect precision to achieve higher resolution. Anyone know what became of this?

      Truthfully, though, as far as IMAX is concerned, I would rather see it on true film rather than a digital projection.

  2. 4k can benefit greatly for theaters, but not as much for home theaters, unless you have a huge screen relative to viewing distance. Most people sitting in a theater would easily be able to see every pixel in 2k regardless of where they sit. However, for 4k, only the people sitting in the first few rows would be able to see every pixel discreetly, meaning the image is extremely life like for most of the theater.

    The fact is, it doesn’t matter how many pixels you see on the screen, it matters more if you can’t see all the pixels. With 4k, most people wouldn’t be able to discreetly see all the pixels, while with 2k most could, so there’s an obvious benefit for 4k. The point is to hit the limit for human vision, and in most cases 2k doesn’t hit that limit.

  3. Jane Morgan

    2k, 4k, 8k, ignore resolution.

    With a 150″ screen, what’s the closest comfortable viewing distance?

    For an action movie.

    What is the limit of the human eye at that distance?

  4. TJ

    150″ Diagonal or wide? 16:9 or scope? If 16:9 and diagonal that is just under 11 feet wide so depending on preference I don’t see why you couldn’t be ~11-12 feet away. Closer if you really want but it maybe hard to pay attention to the entire screen if you get to close.

  5. hurin

    I don’t get 4k at all. No material is available in 4k. Bluray is 1080p, and if you show that on a higer resolution projector, the projector is just going to create the extra pixels out of thin air. Why should that possibly give you a better experience than an ordinary Full-HD projector?

    I found the part about increasing the frame rate interesting. The problem is it would only apply to new movies. Blade Runner on bluray is vastly superior to DVD, but we are never going to see it in 60fps.

  6. Jane Morgan

    Josh, what’s your screen size / viewing distance?

    What is the closest you can sit before it becomes uncomfortable?

    If 8k existed, i.e. Blu-Ray 2, 4320p, what is the closest you would ever sit?

    I sit 7 feet away from a 50″ 1080p plasma. Sitting closer hurts my eyes.

    Would I sit 21 feet away from a 150″ diagonal 16:9 screen? 15ft? 12ft?

    At what point with 8k materiel is viewing angle the bottleneck?

  7. The fact is that as a matter of pure “FACT” the higher the resolution the bigger the screen has to be to display said resolution. Granted there are displays like the one on the new iPhone that fit more pixels in a smaller space but for the LCD and Plasma market those displays have a set number of pixels that (financially) fit into only a certain amount of space and when you add additional pixels in the case of moving beyond 1080p you MUST grow the size of the display to show these extra pixels.

    The only true way to get the absolutely best picture from a set is to display content that was “created” at the native resolution of the display, such as 1080p and make sure the set is natively running that material at the framerate it was produced at. Anything else starts introducing information that was not originally in the content. Films are generally at 24fps normally and Blu-Ray has a method for showing the actual 24fps stream without introducing anything into the picture.

    Watching 24fps movies on a 240hz TV set for example uses an algorithm to add additional frames at spots within whatever you are watching. While Video games and movies that were produced using pure CGI like Cars or Toy Story can sometimes look better, it’s not the true representation of the original material. Video games aren’t an issue but for films you want as close to what the director or creators intended. And adding extra frames are not what videophiles or the directors and cinematographers intended.

    The Home Theater market is flexible and so are people’s impressions of how a film or content looks on a set. There are many variables but the fact is that NOTHING short of demo material is available in 4K much less 8K so for the Home Market which this site is dedicated too, talking about or demanding 4K or 8K is pointless. It took the TV and Movie industry 20 years to finally get HD into our homes and they still screw it up more times than not. Screwed up aspect ratios, poor encodes on catalog titles and even movies made in the last 10 years prove that unless time and care are taken it won’t matter what your resolution is because the end result will be crap.

    So if I were you I would focus on getting the studios to standardize on the current technology before I would be clamoring for yet another thing they can gouge you on and get wrong at the same time. Let’s enjoy what we have for a few years and get it right. As it is it’s gonna be a while before 3D can even get settled and now we’re talking about 8K 3D, jeez.