IMAX Enhanced: first look at HDR10+ 4K Blu-ray

IMAX Enhanced isn’t a new disc format – it's more of an extension to Ultra HD Blu-ray, as to be a full new format it would have to be included as mandatory on all players and be ratified by the Blu-ray Disc Association. But it will still get some die-hard AV enthusiasts excited, and has certainly impressed me.

IMAX Enhanced is a set of features that go from content to screen, starting with a specially encoded Ultra HD Blu-ray disc, to a TV or projector with an IMAX Enhanced mode, as well as an audio processor with an IMAX audio mode.

IMAX and DTS, which have co-launched the format, say the aim is to 'introduce IMAX digitally re-mastered content for the home environment to provide the sharpest 4K HDR images and powerful, immersive sound as the filmmaker intended.'

Armed with an Arcam AV860 processor, which has recently been firmware updated to support IMAX Enhanced, I sampled one of the first disc releases (a second, A Beautiful Planet, launched on the same day in the US). Journey to The South Pacific is a documentary film that has only ever been shown in the largest IMAX theatres, and promises to be a tour de force of image quality.

Other audio brands onboard the IMAX Enhanced train are Denon and Marantz, with supported models including the Denon AVR-X4500H, Denon AVR-X6500H and Marantz AV8805.

What's also noteworthy about IMAX Enhanced is that this disc is the first available using the dynamic metadata HDR10+ HDR standard. Its industry standard cousin HDR10 works and is fine, but an issue has been that 4K HDR TVs have made a mess of tone mapping HDR10 content (this is when the display cannot achieve the peak brightness of the image, so it has to mathematically rework the image to a lower brightness but retain the visual dynamics). HDR10+ feeds the display in real time with image brightness information on a scene by scene basis, in a very similar way to Dolby Vision.

It has been suggested to me that all 4K discs in the future will be HDR10+, as it meets the mandatory requirements of HDR10 and provides the enhanced screen brightness info for the TV/projector to recalibrate scene by scene. This would certainly be a good thing.

HDR10+ compatibility
My the first impression of HDR10+ is that in some UHD Blu-ray players it doesn't work. And I don't mean that the players couldn't read the HDR10+ encode: they weren't able to handle its HDR10 core. I tried a Sony UBP-X800, Oppo UDP-203 and Panasonic DMP-UB900, all with the latest firmware. All saw Journey to The South Pacific as SDR and with a REC.709 colour space, not the BT.2020 HDR it is on the disc.

I got the Oppo to work with it by forcing its HDR detection, at which point it sent out the HDR10 stream, and I understand from Oppo that a new firmware update is coming that will make the UDP-203 and UDP-205 machines HDR10+ compliant (so they will join Panasonic's DP-UB9000, and be followed by Pioneer's UDP-LX500 and LX800 in 2019).

The disc played out in HDR10 (but not HDR10+) from a Samsung UBD-M9500, and in HDR10+ via a Panasonic UB9000.

The other side of the IMAX Enhanced coin is the DTS:X IMAX sound profile. The Journey to The South Pacific disc has such a track and all my players except the Panasonic UB9000 and Oppo UDP-203/205 failed to play it in this format. Again, firmware updates should solve this.

I understand the first studio release in HDR10+ is Bad Times at the El Royale.


Journey to The South Pacific AV performance
The IMAX Enhanced disc peaks at 110Mbps, which likely makes it the highest bitrate-encoded disc to date. Now, throwing this many bits at a poor picture would be pointless, but that's not the case here – the image is truly an amazing 4K showcase. I can see why this title was chosen; it demonstrates how much potential there is in 4K (and makes you wonder why we are talking about 8K...).

I viewed it on a Sony ZD9 LCD, Panasonic FZ952 OLED and Barco 4K DLP digital cinema PJ. The image looks photorealistic and is the first time I have seen a home format look like anything we see in the post-production world. Nothing appears enhanced or pushed. The colour grade is like a Kodak moment throughout. Just get this disc for the images alone.

Another facet of IMAX Enhanced is its use of full frame. This term means anything that fills the full height and width of the container, in this case 16:9 or 1.77:1. IMAX is reliving a battle from the 1950s, which was VistaVision vs CinemaScope. VistaVision had the tag line 'We have the height', an argument that IMAX is using, playing to people who don't like black bars on their tellies. IMAX Digital is 1.9:1, very close to 1.77:1 compared to the 2.40:1 ratio that most filmmakers use. I can see why IMAX has chosen Sony 4K projectors as a partner as these have a 4,096 by 2,160 chip that is 1.9:1 ratio and would match IMAX Digital pixel for pixel. But unfortunately I'm yet to see that as the IMAX Enhanced projector updates haven't surfaced.

So what difference did HDR10+ make? In some scenes, shadows were better defined and the overall picture had a more consistent contrast punch. What it's doing is subtle, but undoubtedly a step in the right direction, as HDR10+ should have been the standard from launch.

Sound-wise, the Journey to the South Pacific platter also impresses. It has that natural history film sound, a bit in-your-face, as most if not all these films are shot mute with audio post-produced. This helps to show off some of the IMAX Enhanced sonic features, one of which is a bass roll-off to try and recreate IMAX cinema sound where full-range speakers with no subwoofer channel are employed. It is very effective and a clever use of the DTS:X metadata to steer the DSP. Sonically this disc is a bit over the top, but as an example of what the system can do it's perfect.

Obviously, what we want to see is how a studio film translates to IMAX Enhanced. Journey to the South Pacific is only 40 minutes long, which means it's hardly touching the sides of the disc. Most feature films are two hours and would need a BD100 platter to have anywhere near the same bitrate offered here.

My reaction to the first IMAX Enhanced disc is overall very positive. Okay, the only bespoke part I could test was the soundmix as there are no displays available yet that are IMAX Enhanced image-wise, but it does unleash HDR10+ into the wild. Is it just another THX? On this early evidence, it might be better thought of as Ultra HD Blu-ray Plus...