The quest for higher quality images is as apparent as ever at the IBC show in Amsterdam, with 4K now prevalent and 8K ultra-high-definition images becoming more evident. So it is surprising to see so many pictures compromised by being over compressed. IBC presents a contradiction. Half the halls are filled with people that appear passionate about achieving the highest technical quality. The other half are apparently indifferent to the result.
Once again, NHK has been leading the advance to the higher ground, showing its 8K Super Hi-Vision in the Future Zone. This already a reality in Japan, where it is broadcast on satellite using HEVC compression.
NHK has also been working towards terrestrial transmissions in 8K, although that will require increased compression. A demonstration using the next-generation Versatile Video Codec, suggested that 8K video could fit within a terrestrial broadcast multiplex, without compromising on picture quality. VCC is currently in development and it will be several years before it becomes commercially available.
Meanwhile, NHK modestly showed outstanding examples of 8K programming in a variety of genres, including drama, documentary, entertainment and sport. It looks beautiful.
This is no longer a science project. Some 8K kit is now commercially available. Some of it is relatively affordable. Blackmagic has an 8K switcher, available for under £8K.
That is not to say that 8K is ready for general use, but it looks like it will be in a few years.
Not to be outdone, BT showed a rugby match live in 8K, although the native 8K was limited to a single Ikegami camera, supported by other 4K feeds. The result of this stunt was shown in a tent on a Samsung 75-inch 8K display.
So do not expect to see a full 8K service from BT Sport real soon now, but it shows what is already possible.
Indeed, the Tokyo Olympics in 2020 will be partly covered in 8K, although only a limited number of viewers will be able to see it that way.
IHS Markets forecasts that in 2020 only 62,000 Japanese homes out of total of 51 million will have an 8K capable TV.
Of course, acquiring at higher resolution will still benefit viewers watching in 4K or even HD. A downscaled image will still appear crisper, without the artificial over-sharpening associated with traditional television pictures.
For those fortunate to have an 8K display, 4K pictures can be intelligently upscaled to take advantage of the additional pixel density.
Resolutions higher than 4K are already being used for some drama and documentary productions. The additional resolution can be used to digitally stabilise shots, allow creative reframing, or support both cinema and television aspect ratios.
Some applications, seamlessly blending multiple screens for giant projections, may require resolutions well beyond 8K.
At 7680×4320 pixels, 8K is equivalent to around 33 megapixels. That is less than the resolution of some high-end still cameras, which can deliver 40, 50, or 100 or more megapixels of resolution.
The effective limit may be the optical ability of lenses to resolve more detail without distortion.
Many lenses used for television and video have been able to deliver impressive zoom ranges, with any limitations masked by the relatively low resolution of broadcast standards.
Lenses optimised for 4K or beyond may be required to deliver the full resolution of ultra-high-definition television. Cinematographic production typically involves prime lenses optimised for fixed focal lengths.
The sharpness of an image is not simply a matter of spatial resolution but of temporal sampling.
Higher frame rates can deliver visibly sharper images of moving subjects, which is particularly beneficial to action scenes and sports coverage.
It may be that higher frame rates will contribute more to improved perceived picture quality than higher spatial resolution under typical viewing conditions.
Another popular claim is that high dynamic range images offer more apparent benefit than higher resolution. It is certainly true that the limited range and levels of luminosity of legacy television and video systems is far less than can be supported by current image sensors and some displays.
Improving the quality of acquired images offers greater creative control and enhances the final result, however it is delivered.
Yet if the pictures are over-compressed, the effective resolution is reduced, irrespective of the number of pixels displayed.
Seeing properly produced pictures on a decent display emphasises how poor some of the images that are shown on television are by comparison. People have become culturally accustomed to accepting the inferiority of television pictures.
Leading Hollywood directors have backed proposals for screens to have a ‘Filmmaker Mode’ that ensures frame rates, aspect ratios and colour temperature are set to preserve the intended viewing experience.
This initiative and similar calls for a ‘Netflix Calibrated Mode’ are supported by a number of display manufacturers, to be enabled either though a single button selection or automatically through embedded metadata.
The highest delivery standards are now being set not by broadcasters but by online distributors that that cinematic expectations and big budgets.
It is evident that trade shows like IBC attract many people that are passionate about creating and crafting productions of the highest technical quality.
Equally, there are many that are apparently indifferent to delivering optimum picture quality, despite their claims to the contrary.
So, it is disappointing to see some demonstrations of 4K and 8K pictures delivered at data rates that inevitably compromise quality. It is all the more disturbing when those showing off such images seem sincerely unaware of the obvious artifacts. Never mind the quality, look at the bandwidth.
That is why the ambitions of NHK, not just technically but aesthetically, stand out starkly among broadcasters and continue to impress.