Any video disc standard of past has taken time to shine. Both DVD and Blu Ray in fact took a year to start producing content that was better than the previous standards – VHS and DVD respectively. I remember the first round of Blu Ray discs: barely better than DVDs when the DVDs were played on top of the range hardware having the best chips for cleaning, filtering and sharpening the image. What I have seen with UHD Blu Ray is déjà vu all over again.
UHD Blu Ray – the Theoretical Benefits
There are three major benefits of the new UHD standard that should theoretically overshoot Blu Ray by a large margin:
- 4K Resolution: 4x the pixel density of Blu Ray resulting in a much sharper image.
- Wide Colour Gamut (BT.2020): a much wider range of colours that can be displayed on screen resulting in more realistic colours when used correctly.
- High Dynamic Range (HDR): giving the image more contrast, more depth, and a much higher range of brightness variations depending on the display the disc is played on. The brightness variation is not only in the highlights – for those in the know – as that is only the recommendation for use. However, HDR is already being used in more creative ways.
The Reality Today
Unfortunately, a year on we are still waiting to be amazed by the new standard and here is why:
- Standard Blu Ray is a very mature technology. In fact, the video compression technology (AVC or H.264) for standard Blu Ray has had more than 10 years to mature to ensure image quality, integrity and sharpness are at their optimum. The compression technology for UHD Blu Ray (HEVC or H.265) on the other hand is still in its infancy by comparison. It has not reached the same level of efficiency in its ability to keep all the detail in the picture as AVC has, nowhere near in fact. [note: HEVC is more efficient than AVC but comparatively looking at its own life-cycle it isn’t at the same maturity!] There is a lot more to come from HEVC in the coming years. However, we are now at a point where HEVC is starting to shine.
- The Blu Ray players, upscaling chips and upscaling technologies we have for standard Blu Ray have also had 10 years to mature and have they matured alright! We have image enhancement technologies using contrast enhancement (Darbee) as well as Super Resolution algorithms (e.g. JVC’s Eshift, Sony’s Reality Creation) that when used together easily rival UHD 4K images by analysing information on pixel by pixel and frame by frame basis to fill in the missing pixels.
- The data-rate used for the first round of UHD Blu Rays is still only at just above standard Blu Ray levels. This is because only the 50GB and 66GB UHD Blu Rays have been efficient enough to manufacture. The promised 100GB discs are not yet standard. This is a huge drawback.
- The compression (or authoring) software used to make UHD Blu Rays is nowhere near as mature as it is for Blu Ray. This means compressionists have had less control over where bits are allocated for the most optimal picture quality for these first year discs.
- However, even if they used the new 100GB discs, the images wouldn’t be sharper. In fact, around 95% of movies released on UHD Blu Ray in the first year were sourced from 2K masters upscaled to 4K as opposed to proper 4K images. This is partly because most films – especially that need heavy CGI – upto now have been finished at 2K resolution. To go back and re-do the CGI at 4K would be very costly. However, the trend is now changing due to the 4K push.
- Even if a movie is finished at 4K, we know from working with standard 1080p Blu Ray that the best examples of the format are those discs that have been sourced from imagery 4x the resolution: in this case 4K. This is because there is more information to work with when cleaning up the picture for digital storage. Also, more high-frequency information – and therefore finer detail – can be captured by downscaling an image from a higher resolution digital source. So it stands to conclude that the best UHD discs will come from digital intermediates (DIs) that are at least 6K or higher resolution. In fact this is what we see as the best examples of the format. More on that in a moment.
If the difficulty of getting the imagery captured, prepared and compressed wasn’t enough, there are a few design and few teething issues with the format as well:
- HDR as designed for UHD Blu Ray only takes into consideration flat panel TVs and not projection. This is an oversight of massive proportions. It isn’t even that the cinema HDR standard wasn’t ready, as Dolby Vision (one of the HDR standards) is used for Cinema HDR in the US. Even Dolby didn’t push for this to be in the standard, as Dolby Vision for UHD Blu Ray and in the cinema are two different standards. Having said that, a year on we have ways to calibrate projectors that emulate Dolby Vision or HDR10 (the most commonly used HDR standard), but it is not fully accurate to what the director intended. In fact, we have no way of getting fully accurate imagery for projection for HDR at this point.
- HDR10, the most commonly used standard, has had no dynamic meta-data until recently. Dynamic meta-data is required for HDR as the mastering displays that UHD Blu Rays are created on have vastly different performance characteristics than our TVs and projectors in the home. Our TVs and projectors have a fraction of the colour palette or brightness to play with when displaying the images, therefore we need a way to tell the display how to interpret the data to be accurate to what the director intended. Dolby Vision has this information but HDR10 is now catching up, slowly.
- The Wide Colour Gamut should be something that allows a more accurate representation of what we see in the cinema. The cinema standard colour gamut, DCI P3, fits into the colour gamut of UHD Blu Ray (Bt.2020). However, instead what has been happening in some cases is movie studios thinking they should differentiate the UHD Blu Rays by “turning colour up to 10” and using a palette that at times does not look natural, or faithful to the cinema presentation. They do this to give you more of a “thrill”, however, this is where immaturity of using the format shows. It destroys the original creative intent.
The Future Starts Now
I believe the future is here. We are now starting to see UHD Blu Rays that are in fact bettering Blu Rays by a wide margin due to some of the above issues having been addressed. I will mention two that have just come out, almost exactly a year after launching the first round of UHD Blu Rays:
- Planet Earth II: this BBC series was captured at mostly 6K resolution using some of the best cameras and downscaled to UHD Blu Ray. It really shows what the format can do today.
- Passengers (2016): this heart-warming Sci Fi was also captured at over 6K resolution and downscaled for capture onto UHD Blu Ray. What’s more, the movie’s colour palette is faithful to the original cinema presentation. This is how UHD Blu Ray should be done, ladies and gentlemen. The presentation is a nice cut above Blu Ray.
What’s Next for the Format?
As we have seen with Blu Ray and with DVD before it, UHD Blu Ray is just coming into its teenage years. The format still has a lot of road to travel and we can expect the following as it matures:
- Compression technology, HEVC, will improve further over the next couple of years to be more efficient and also to produce sharper and more nuanced images.
- Authoring software will improve to provide optimal bitrate to the right places in the bitstream.
- 100GB discs will become the norm providing almost twice the bitrate of today’s disks.
- Image enhancement technologies such as Darbee and Super Resolution algorithms will be adopted for 4K images, bringing out even more detail in the picture.
- The majority of movies will be scanned and then finished at 6K and even 8K resolutions, providing the best starting point for retaining high-frequency detail and therefore image sharpness.
- HDR technology will continue to mature both in its implementation and in its use by movie studios.
- Movie studios will stop playing with Wide Colour Gamut as a new toy and will respect the creative intent and integrity of the original works.
So in conclusion, we haven’t yet seen the best this format will be able to do. The format has a lot of headroom to improve – in fact more than previous technologies – and we will see some phenomenal picture quality from this format over time.