Budget TV resolution rumble: 720p plasma vs. 4K LED LCD

If resolution is as important as some say it is, then this should be no contest. On one side, we've got a 50-inch Ultra HD 4K LED LCD. On the other side, we've got a 720p plasma. A $500 50-inch plasma.

Head-to-head, with a variety of content and objective measurements, how do they compare?

The results may surprise you.

These TVs are perhaps more similar than they first appear. The Samsung PN51F4500 plasma is the cheapest of its kind: a bare-bones, 1,024x768-pixel "720p" entry-level model. The Seiki SE50UY04 LCD is also one of the cheapest of its kind: a bare-bones, 3,840x2,160-pixel "4K" entry-level model. LCDs are typically more expensive than like-size plasmas, and 4K TVs even more so.

I placed these two TVs side by side, and fed them a variety of signals, through a Monoprice HDMI splitter. I sat at different distances. Both TVs were calibrated, or at least as much as they could be.

Strengths and weaknesses
Initially, I tried out some 1080i content from AT&T U-verse. I suppose I could have started with DVD, but who cares about DVD? I sat at roughly 9 feet from both TVs.

With Sorkin's latest wordfart "The Newsroom," the Samsung's better contrast ratio made it the clear winner. The Seiki looked washed out and flat. Shadows and black objects looked gray. The Samsung looked more real. There was very little difference in apparent detail. As I've mentioned before, but it bears repeating, I have 20/15 vision. This is better than the normal visual acuity of 20/20.

Neither TV has very good processing, so more poorly encoded/higher compressed content, on HBO and other channels, didn't look awesome on either TV. The Seiki looked more smeary, while the Samsung had combing artifacts thanks to mediocre deinterlacing.

The scaler in the Seiki isn't great, so using a Samsung BD-F7500 I sent the Seiki an upconverted 4K signal of "Avatar." Using an Oppo BDP-93, I sent the Samsung 1080p from another copy of the same disc.

This is where you'd expect things like textures in objects, hair, and wrinkles to really pop out on the Seiki, except...the Samsung looks just as detailed. In some cases, it looks more detailed.

WTF?
There are a few things going on here, as to why the extra resolution potential of the Seiki isn't translating to extra visible resolution. The first, and most important: I'm too far away.

I've written multiple articles about this, as have many others, but the fact is, your eye has finite resolution. From a certain distance, your eye can't resolve the difference between 1080p and Ultra HD. With TVs this "small," your eye can't even tell the difference between 720p and 1080p, never mind 4K. So all the extra pixels on the Seiki are wasted. If you're curious if you'll be able to see the difference from where you sit, with your eyes, and whatever TV size you want to get, check out Chris Heinonen's excellent 4K Calculator.

Why was I sitting at 9 feet? Studies have shown that most people sit between 9 and 10 feet from their TV (called the Lechner distance). If you sit closer, good on ya, but you're on one of the slopes of the bell curve. Personally, I usually sit 8 feet away from a 102-inch screen, so I'm way on the flat tail of the curve. At 9 feet, 50 inches is way too small to need more than 720p resolution. At that distance, 4K has dubious merit even on a 60-inch TV.

There's more to it than that. The Seiki, like all LCDs, has motion blur. This is when any object in motion (even the entire screen itself, when the camera pans), blurs slightly. Higher refresh rates were developed to counteract this, though the processing involved can result in the dreaded Soap Opera Effect. Not everyone notices motion blur, and not everyone who can see it is bothered by it. I notice it, and it bothers me. So even though the Seiki might have more pixels, it doesn't have great motion resolution.

Lastly, your eye is much more sensitive to the contrast of the image. And what is detail anyway? On a TV is it not the contrast between two adjacent pixels? The Samsung has a much larger contrast ratio, so even with the same content, the Samsung will sometimes seem sharper because there's so much more contrast with the image.

Sitting closer
As the science predicts, if you sit closer, things aren't so simple. All the issues with the Seiki are still there, but the Samsung now has the added negatives of video noise (likely dithering, not noticeable from farther away), and on brighter images, you can start to make out the pixel structure. With my 20/15 vision, I started to notice some of this from about 7 feet away, and closer than 6.5 it was definitely noticeable.

How objectionable it was, is much more subjective. If I were sitting this close to a 50-inch TV normally, I'd probably spend a bit more and get something with 1080p resolution like the S60 Panasonic. As in, still forgoing 4K, but sticking with the better contrast of plasma.

Sitting this close, and with the Samsung-scaled image, the Seiki definitely seems a bit more detailed. All the things you'd expect to see more of, like textures, wrinkles, facial hair, etc, are a little more noticeable on the Seiki (at least with shots where there isn't a lot of motion). Though it's still not the night-and-day difference we all got to know during the transition from SD to HD.

By the time you're really close enough to get the most out of a 50-inch 4K TV (less than 5 feet according to the math and calculator), you can definitely make out the Samsung's pixel structure to the point where it's not worth watching.

Beyond
Would sending the Seiki a better scaled image been better (the Samsung BD player is good, but not the best)? Would sending both TVs a native 4K signal been better? In both cases, I doubt it. With how it was set up, there should have been at least some indication the higher resolution was worthwhile at a normal viewing distance. Since moving closer revealed more detail, it's clear the TV was more detailed, but that even my trained 20/15 eyes couldn't make it out from 9 feet.

At worst, the Seiki was showing a source (1080p) with more than twice the pixels the Samsung even has. With upconversion, it was at times showing something with more than 10 times the number of pixels of the Samsung. Yet...it didn't seem more detailed from where most people sit.

Would a better 4K TV have done better? Certainly. But what to put it up against? How about a 4K Sony XBR-55X900A vs. the Panasonic TC-P55VT60? Why stop there? For more similar money, how about Samsung's own UN55F9000 4K against its KN55S9C OLED? Anyone who has seen the latter wouldn't hesitate to declare it the winner. David Katzmaier has seen lots of 4K TVs, and he said the 1080p KN-55S9C had the "best picture we've ever seen."

Overall (it's about contrast ratio)
When it comes down to it, it really is all about contrast ratio. I measured the Samsung's contrast ratio at 8,382:1. I also measured the Seiki, and it was around 3,000:1, plus a little more from some pretty mediocre "local" dimming from its edgelighting LEDs. This is a pretty significant increase (forget all contrast ratios supplied by manufacturers, they're made up). The black level is significantly better on the Samsung as well, around 0.005 foot-lamberts to the Seiki's 0.025.

On bright scenes, your eye is naturally drawn to the Seiki, because it's about twice as bright as the Samsung, and there's no way to turn that down (74.3 vs. 41.91 ftL). This is one of the reasons why LCDs outsell plasmas, but brighter isn't always better.

The images above (and below) tell the story. A display with a higher contrast ratio is going to look better than one with just a higher resolution, presuming you're not sitting so close as to see the pixels.

Bottom line
What was the point of this exercise (other than it amused me)? To demonstrate that resolution is not nearly as important as it seems. Sure, it's an easily comparable number, and we all remember how great that first glimpse from HD was. But 4K is different. It's not nearly the increase that SD to HD was, and HD is already a lot of resolution. More, in fact, that most people need (with their seating distance and screen size taken into account).

Contrast ratio is much more important, as is color accuracy, minimal noise, minimal artifacts, and so on. A noisy, poorly encoded 4K image will look no better (or worse) than a 1080p image. A low contrast 4K image will look flat and boring. Many of the Seiki's problems stem being a fairly mediocre LCD. A low contrast, motion-blurred image, completely negates any benefits of additional resolution. That is, unless you're sitting so close (or your TV is so huge) that you'd see pixels with a lower-resolution display.

The real takeaway from this? If you sit close enough, or your screen is big enough, 4K is incredible. But for everyone else, contrast is still way more important. Which is one of the biggest reasons I'm so excited for OLED.

Got a question for Geoff? First, check out all the other articles he's written on topics like HDMI cables, LED LCD vs. plasma, active vs. passive 3D, and more. Still have a question? Send him an e-mail! He won't tell you what TV to buy, but he might use your letter in a future article. You can also send him a message on Twitter @TechWriterGeoff or Google+.