Deborah D. McAdams /
02.20.2013 04:14 PM
HPA 2013: To 4KTV or Not to 4KTV
Resolution Alone is Not Enough
INDIAN WELLS, CALIF. – Why bother with 4KTV, or UHDTV, or Ultra-HD, or whatever name implies the developing generation of higher-resolution television? One of the key questions is whether or not anyone will notice the difference, and if it’s significant enough for people to go out and drop a dime on a new TV set after just paying off the HDTV. The European Broadcasting Union set about to find out.

“The first think the EBU tried to determine is if viewers could see the difference,” said Hans Hoffmann, EBU’s head of fundamentals and production.

The EBU assembled 72 volunteers at one of its own conferences to test UHDTV, using what Hoffmann referred to as UHD-1 material—3,840x2,160 pixel resolution images collected at 50 frames per second collected from Sony F65 test shoots. It was cropped from 4K to 3,840 pixels horizontally. Copies were down-converted to make the HD-UHDTV/4KTV comparison. HD resolutions used included 1080p/50, 720p/50 and a conversion of the 1080p/50 to 1080i/25 using an HHI filter and subsequent de-interlacing.

Test footage was run on a 56-inch “UHD-1” monitor that was not, “Grade 1,” Hoffmann said. Six sequences were shown of the four resolutions, including UHD-1. Two viewing distances were used—1.5 times picture height, the standard distance for viewing UHD-1, and 2.7 meters, the average domestic viewing distance in the United Kingdom.

Samples were shown in 12-second sequences. Participants were asked to rate them bad, poor, fair, good or excellent.

Between 720p, 1080i and 1080p, there was no conclusion of perceptual difference. There was a “statistically relevant, but very small,” perceived improvement of native 4K content when it was presented on a UHDTV screen,” Hoffmann said.

“The results are only applicable for uncompressed sources,” he said. “Transmission compression may change results significantly…. In order to create an immersive impact, resolution alone will not make the difference… to make consumers go into shops and buy theses screens.”

More frames are also necessary for motion portrayal, and so the full distribution eco-system must be able to handle higher frame rates. There are cameras and displays for 60 fps, but nothing in the middle, he said. The same goes for higher dynamic ranges.

Motion-blur improvement with a higher frame rate would still be perceived at higher viewing distances,” he said. Object high-dynamic range improvements likely would be perceived, as well as object color improvements and higher bit rates.  

For now, he provided the following advice: Relax. HDTV investments remain valid.

“UHDTV is a mid-longer term development,” he said.  


 



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1.
Posted by: Anonymous
Fri, 05-22-2013 06:05 PM Report Comment
Thanks for sharing this. This week I made a few 4K demos using the Sony 4K server connected to my Sony 4K projector, the purpose was to write a review on both but I invited a variety of viewers from the installation and sales video industry. I used a 110-inches screen viewed from 15 feet away, which is even more than the recommended HD 3xPH distance and certainly beyond what 4K is suggested. 1080p content was upscaled to 4K by the Sony projector and was consistently appreciated as a stunning image even with the 130 inches Cinemascope clips. The 4K clips were considered too real, that is the feeling: a sense of realism, not just a great image, not just seeing or not pixel structure due to eye's acuity. Is the overall impact of realism. And that is a with a 4K that is just using 8-bit, 4-2-0, Rec-709 color space, and 24 fps. The potential is much higher than that in all counts. I noticed a similar experience than with any hi-end audio or video system: content that is not recorded with its expected excellent quality for the format is immediately noticed as that something is missing. In this case, even using the 4K F65 cameras, some minor drop of proper illumination, a bit out of focus, not the right depth, too fast pan, etc. made those seconds on a 4K clip look as 1080p Blu-ray. This is similar to when we started with HD in 1998, requiring a new approach for make-ups, light, shots, etc. In other words, proper quality in the 4K content(or even in 1080p when upscaled to 4K) is imperative for viewers to notice the difference, but the difference is too obvious to ignore it, we just have to implement it right from the content forward. Creating a good 4K camera or a stunning 4K display are just two items of the chain, the difference will be noticed in how do we connect the two. Not to mention the harm of using excessive compression on an otherwise excellent 4K content just to make it fit in the old jar. Best Regards, Rodolfo La Maestra
2.
Posted by: Anonymous
Sat, 32-23-2013 02:32 AM Report Comment
To be a fair test, they should have shot with the 4K camera and 1080p and 1080i cameras side by side. (Or, theoretically, they could have shot 8K and downconverted everything from that.) The 4K in this case is stuck with making its Nyquist limit using an optical low pass filter, while the rest of the formats benefit from oversampling by making their Nyquist limits with digital filters. That people don't see much difference merely proves what a good thing it is to oversample.




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