Live production in UHD
By Yeray Alfageme, Business Development Manager at Optiva Media an EPAM company
A lot has been discussed here about the technical implications of using new formats such as UHD in our live productions. And it is clear that it is one of the aspects that changes in a greater deal and in which we must learn the most. However, technique is nothing if it does not tell a story. Let’s see what implications 4K and 8K, UHD, WCG and NGA can have, not as regards of technique, but in telling stories, which is what matters.
More definition, more reality
Let’s start by the definition. We already know -because we’ve done a lot of dissemination about it- that UHD is not just 4K, but much more. However, the definition is the aspect of these new formats that is easier to understand and manage by both professionals and consumers. For this reason, increasing definition has implications on what we see and how we see it beyond seeing it better.
If we increase the definition and allow more details to be seen, we may be showing things that were not seen before and that we did not want to be seen. Perhaps we would not look at them because the technique did not allow us to show them, so the technical limitations were of help, but now we have to be careful. From a more elaborate makeup to a few more refined sets, planes or movements are necessary now that we are approaching -or perhaps exeeding in the case of 8K- the definition that is actually perceptible by the human eye.
And more definition does not always imply better stories. It is necessary to remember that sometimes we want to show reality, as it is the case in news or sports, but sometimes we want to tell a story, even in a live broadcast. That is why we must take into account the new tool we have at hand.
The main implication of an increased definition lies in the composition of the plane and camera movements. It is not necessary -it must be even avoidable- to make movements, both from camera and zoom, as abrupt as we used to do in HD. With such high definition, viewers cannot appreciate everything we show them, it can even become confusing. With such high definition it is necessary to “move through the plane” so as to be able to see everything. We must allow viewers a prudent time to walk through the image and look at what we want them to look at, not force them to do so.
The second consequence: field depth
And very close to definition comes field depth, the space between the first and the last sharp or focused object. Because with greater definition an increase in field depth is implicit. This goes against a trend that has been going on for some time now that encourages -even the smartphones in our pockets offers tricks for this- to decrease filed depth in our planes.
But what is the goal of decreasing field depth? In addition to being something fashionable and more or less transient, it helps to focus attention on a point within the image; it provides more drama to the shot and even brings viewers closer to the action. There are two ways to decrease the depth of field: increase the focal length -zoom-, with which we modify the frame itself, or increase the opening of the diaphragm, with which we modify the exposure and brightness of our scene. Both aspects have implications in the composition of the plane that cannot be ignored.
We will always have to strike a balance between achieving the desired field depth and showing what the new definition allows us. Later we will delve in the implications of using the same planes in dual productions, HD and UHD -which at first glance are a lot, but in practice not so many- in which the depth of field has much to play.
The HDR, seeing more with the same number of pixels
It has always been said -and I agree- that HDR is the “wow effect” of UHD. And it has been proven, even in studies carried out by the BBC and the EBU, that viewers prefer an HD-HDR image over the same 4K-SDR image. There must be a good reason for this. Because the main difference between what our eyes see looking at the advantage and what we see through a screen is not so much definition but the dynamic range, the luminosity, that we can appreciate.
Until today if we did a high-contrast shot -the most classic example being a football match in sun and shade in the middle of the afternoon- we would have to choose between showing the sun or the shade, in addition to conveniently hydrating our camera controls for the constant effort and continuous adjustment they had to make on the exposure of all our cameras. Never again with HDR.
Whether HLG, more widespread in live productions due to its backwards compatibility with SDR and the static metadata that allows interchange more easily -as in Dolby Vision or any other PQ curve with dynamic metadata that are much more capable but complex- every HDR format allows us to show an image much closer to that captured by the human eye and shows much more than an increase in definition, Fact.
This drives fiction creatives mad as they used to rely on shadows, and even lights, to hide what they did not want to show in a scene. It also has implications for live shows as it prevents focusing the lens of our image on a point so much. Showing more, in a similar way to what happens with definition, forces viewers to assmilate more information and therefore more time and more effort are needed; we must allow for this.
In the beginning, when we did not understand very well what we could do with HDR, its effect would be exarcebated, even exceeding the eye’s dynamic range; not so much so. At the other end would be those trying to increase contrast to give up some HDR effect as they would feel more comfortable controlling a “traditional” SDR image. Just as well we are learning fast.
Today we have learned to use HDR in a way that we are able to offer viewers a much more natural image, very similar to what it is seen in the real world, helping them to focus the lens on the desired point of the scene. This is not only achieved with the luminance control, but is a combination of definition, field depth and dynamic range. The latter is now controlled, although there is still a long way to go.
WCG: yes, color also counts
If definition is highly praised in UHD, color has been mostly neglected. Yes, color matters too. Because the color space 709 that we had before in SDR, as defined by the number of colors that a traditional SDR monitors could display -which is not bad- has not been just left behind, it has been blown to bits.,
From a space of color that allowed us to show only 35.9% of the spectrum of color visible to the human eye, such as 709, we moved on to one that allows us to show nothing more or less than 75.8% of all the colors of our visible world, 2020. And this goes beyond mere doubling the number of colors, as now our palette moves in a space that is three times larger, so, again, we must make choices that we were not previously making.
From saturation or hue in our scenes to white balance, although the D65 white point remains in both color spaces, these are components of our image where we now have much more room for maneuvering and also less room for error. With limited color space, viewers found it understandable that colors were not the same and even allowed certain changes from one camera to another. But now these mistakes can be much greater and also less acceptable, since we have already shopwn them how well we can perform. If you give me lobster, I won’t like pea soup anymore.
Conclusions, if any
It is hard to summarize in a couple of paragraphs what artistically implies the change of format from HD to UHD in our live broadcasts, but if you skim over these lines again, you will spot a common element: we have many more tools at our fingertips now.
And having more tools implies more responsibility, having to make more decisions and investing more effort. Although perhaps not everyone is willing to do so. Many of us used to complain that we couldn’t see the shadows before or that the colors weren’t “natural”, whatever this means. Now that those technical limitations have been removed, the thing has become more complex.
And no one said the future would be easier, they just said that it would be better. And UHD is better than HD for our live productions, no doubt, but there are many more choices to make, information to show or hide, and that takes an effort.
For years and years, we have worked to achieve great results despite the limitations of technology. Well, now those limitations have disappeared. So, our adaptation does not apply, we must learn again. One thing is for sure, viewers so appreciate innovation and evolution as long as we offer them the rght implementation of these. The “HDR effect” is a bad example of this.