8K Upscaling Reviewed Part 2
In the first article we published on upscaling technology, we looked at the theory of upscaling. This article will dig a bit deeper into the practicalities of upscaling. One of the questions is, where is it best to do the upscaling?
We’re going to look at a typical UltraHD Blu-ray configuration in an enthusiast’s home. UltraHD Blu-ray is currently, unquestionably, the best mainstream source for high-quality content to act as a candidate for upscaling (if we exclude the exotic disk-based home cinema server systems). That’s because the high capacity of UltraHD Blu-ray allows bit rates from 72 Mbps to 144 Mbps, so content does not need to be compressed so strongly. (Blu-ray is not being extended to support 8K content because of the move to content delivered via the internet rather than by physical media).
A Blu-ray player may be connected directly to a TV, but as far as we could tell at the time of publication, no UltraHD Blu-Ray players have integrated upscaling to 8K. All have excellent upscaling, but they are designed to bring the lower resolution up to the 4K level of the disks rather than going beyond.
It’s unlikely that someone interested in the best video imagery would not want the best audio too. That means that an A/V receiver will likely be in the signal chain. Of course, if you have an UltraHD Blu-ray player and a TV, the TV will do the upscaling to 8K.
But should the upscaling be done in the receiver or the TV set?
8K Scaling in the Receiver
8K receivers are available from Denon, Marantz, Onkyo and Yamaha. The models from all but Onkyo support HDMI upscaling of 4K to 8K. Onkyo supports 8K passthrough but not scaling.
So if you have a new model from one of those three brands, where is the best place to do the upscaling – in the receiver or the set? Is there a way for you to set where it happens? The TV will automatically upscale to 8K if it receives any resolution below, so the question is whether the receivers allow control of the upscaling. The TV will provide the information, via EDID, that it can support 8K input, so the receiver will know that it is connected to an 8K set.
All three brands with 8K upscaling allow the forcing of the output to be just UltraHD/4K and, therefore, rely on the TV to do the upscaling. The Denon and Marantz brands (both owned by the same company) do so in precisely the same way.
So should you force upscaling by the TV?
“The proof of the pudding”, as the saying goes, “is in the eating”. In other words, it’s the result that counts. The sure way to check the best way to upscale is to try setting the receiver to 4K, showing a well mastered UltraHD Blu-ray disk or test disk (such as the Spears and Munsil UHD HDR benchmark) and comparing it to the 8K setting. That’s not easy, as each of the upscalers is likely to have some better and worse features and performance. It can also be hard to remember which is better when you don’t have two side-by-side images.
In general, though, there is a relentless upgrade cycle of annual improvement in the TV set market. That, combined with the considerable volume of the TV market compared to receiver production, is likely to mean that if you have a TV set from a premium brand, the upscaling will probably be better in the TV.
As discussed in part one of this review of upscaling, the significant change in quality has been in the last couple of years with the addition of AI-assisted upscaling. None of the receiver specifications that we looked at made any reference to this kind of AI technology. On the other hand, in their latest sets when we published, Samsung’s Neo Quantum processor, Sony’s Cognitive Processor XR and LG’s Alpha 9 Gen4 all include AI technology.