Megapixel Madness, Now Coming to a Home Theater Near You
For over a decade, photographers have benefited from a “megapixel war” among the various manufacturers of digital cameras. As technology progressed, companies such as Canon and Nikon crammed ever-more sensor elements into their imaging chips.
Generally more megapixels are better then fewer. With more pixels, an image can be printed at a larger size or the user can crop it and still have enough pixels to produce a quality picture. However, there is a point where this “arms race” ventures into the realm of absurdity.
Here’s one example. At HMML, we have a small Canon point-and-shoot camera that has a 14-megapixel sensor. The actual size of the images produced is 4320 by 3240 pixels, impressive by any account for such a small camera.
Doing the math, however, illuminates some of the absurdities inherent in this. The imaging chip in this small camera measures a mere 6.17 by 4.55 millimeters in size. To get 14 million sensor elements in this array means that there are over 700 individual sensor elements per millimeter! Does anybody think that the lens on this point-and-shoot can actually effectively resolve images to this level? Not a chance—this is an example of what I call “more pixels, but not much more detail.” At some point, there are diminishing returns, with the only concrete result being the extra data that the user needs to archive.
But it makes for good marketing hype.
Now this marketing effort is coming to the realm of television in the form of “4K video,” also known as Ultra High Definition (UHD).
To understand UHD, it’s good to review the various television resolutions available today. For most of the history of TV, we’ve had “Standard Definition” (SD) video. The actual pixel dimensions of SD video vary a bit depending on the delivery system used, but it’s often referred to as 480p—that is, 480 pixels in the vertical screen dimension with progressive scanning (each video frame scanned at once and in sequence). This is the sort of video you get on a regular DVD, and it’s important to note that most of the legacy video content out there is encoded at this resolution.
High Definition (HD) video has been around for quite some time now, but there are actually two resolution specifications that qualify for this label. 720P television sets display 1280 by 720 pixels; they are typically the smaller and less expensive TV sets available to buyers. A “full HD” TV set displays 1920 by 1080 pixels (1080p).
Many feature films and television programs are “filmed” with digital video cameras having what is called “2K” resolution; this produces an image measuring 2048 by 1152 pixels. These images can be projected in theaters to enormous size and look gorgeous; of course they also can be slightly downsampled for HD television broadcast with no loss of quality.
And, like the tiny point-and-shoot camera mentioned earlier, I think it’s mostly hype, a technology pushed by the television set manufacturers after their failed efforts to convince consumers that 3-D television sets were the wave of the future.
Paying for Resolution that You Can’t See
The first point I can make about 4K is that for most home television viewers the enormous added resolution of UHD will be imperceptible. Typical viewing distances for television in most homes is around 9 feet (referred to as the Lechner Distance after the television engineer who researched this matter). At this distance, typical human vision cannot distinguish individual pixels in a 46-inch (diagonal screen dimension) 720p TV set. For 1080p, it takes a set larger than 69 inches for a person to distinguish them.
For UHD, with its picture size of 4096 by 2160 pixels, you’ll have to have a 138-inch TV set at nine feet to reach the point where individual pixels can be perceived. That’s eleven and a half feet! A viewer watching a smaller TV set (pretty much everyone) simply won’t be able to see the extra resolution. Since these proposed UHD TV sets will certainly cost more than the HD sets available today, what exactly is the consumer getting for the extra money?
Legacy Video Content Could End Up Looking Worse
At this time, there’s still far more Standard Definition video programming out there than HD. This can be a problem when playing such content on a large 1080p set, as the 480p image has to be upsampled to over twice its original size to fit the higher-definition display. In many cases that I’ve seen, the result can be downright ugly. SD video upsampled to 720p generally looks much better to me—the system doesn’t have to create as many “bogus pixels” to enlarge the image.
What’s going to happen when 480p video is upsampled to 2160 pixels (a factor of four and a half)? I haven’t seen any tests, but this has the potential to be completely unwatchable unless the engineers working on UHD are figuring out some sort of technical workaround. Even full 1080p content will end up being enlarged by a factor of two to run on these new television sets, with the inevitable fuzziness, ragged edges, and other enlargement artifacts.
So, for much of the existing video material available to viewers, buying a 4K TV set could actually end up making things look worse rather than better.
Bandwidth and Storage Nightmares
If you look at the graphic above, you can see that UHD video provides over four times the pixel count of 1080p HD. With standard digital video compression, it appears to require about 3 times the network bandwidth to deliver that video to viewers. For companies such as Netflix, Amazon, Hulu, and others, this means having to store much more digital data for on-demand delivery. For cable TV companies and other Internet Service Providers (ISPs), it means having to build more digital bandwidth to accommodate that data as the market moves inexorably towards more streaming video consumption.
Who’s going to pay for these increased data storage costs and cable infrastructure upgrades? Here’s a hint: It won’t be Netflix, Hulu, Amazon, ComCast, or any of these companies. It will be their customers, folks like you and me. All to deliver pixels that can’t be realistically seen, on expensive new TV sets that might make your existing DVDs look lousy. Who’s the winner here?
Not you and me. However, companies like Sony and Panasonic, and vendors such as Best Buy are going to do their best to cash in on the hype.
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