Philips Eyes First Public Demonstrations of Its HDR System at CES

Like Dolby, Philips stressed that HDR is not about increasing a screen's overall brightness. The aim, it said, is to extend the dynamic range or contrast between extreme bright whites, like the sparkle of jewels, and dark areas, like shadows that contain detail that’s usually lost in a conventional low dynamic range (LDR) picture. To illustrate the benefits of HDR, one of the Philips HDR team leaders, Joop Talstra, standardization manager-Philips Consumer Lifestyle, gave the example of a scene shot in a dark barn, with a door out to bright sunshine. HDR enables the screen to show the detail both inside the barn and outside in the field, Talstra said.

Commercializing HDR has become possible as the efficiency of LEDs has improved, and with the development of local dimming that has resulted, Philips said. HDR is applicable to Full HD as well as 4K Ultra HD, it said, and for its HDR demonstrations in Eindhoven, Philips used a SIM2 47-inch Full HD commercial monitor of the type usually sold to carmakers for computer-aided design. The bare monitor costs about $45,000 and needs multiple noisy cooling fans to deliver screen brightness of 5,000 nits, Philips said. By comparison, Talstra said, most current LCD TVs deliver under 500 nits and even the most expensive commercial displays struggle to reach 1,000 nits, and then only over part of the screen and for short scenes.

The major studios still master and grade color for commercial feature film releases using a 100-nit benchmark, but brightness readings can be deceptive, Talstra said. Movie theater screens deliver only 55 nits, but audiences don’t usually complain because screens are huge and the auditorium dark, he said. In real life, a dark night may register less than a single nit of brightness, but a full moon registers 2,000 nits because all its light is concentrated in a small object, he said. "Our target for HDR is anything from 500 to 5,000 nits, although that is 10 or 15 years out for consumers," said Talstra. Another Philips target is to require only insignificant extra bandwidth for HDR signal carriage, and so permit HDR delivery down the same "pipe" as a conventional signal, he said. Dolby said in Berlin that Dolby Vision content delivery will require about 20 percent more data bandwidth.

Although 12-bit coding is theoretically ideal for HDR, it's complex and costly to implement, Talstra said. So 10-bit coding is adopted as a "good compromise" with careful weighting to take advantage of the eye’s different sensitivity to different colors, he said. Philips has developed software plug-ins for standard grading tools such as Adobe After Effects and DaVinci Resolve, he said. This lets a studio engineer grade a movie twice, with one pass optimizing all scenes for 100-nits display and another pass for 5,000 nits, he said. The Philips system then encodes simple metadata instructions that describe the difference or "pathway" between the two extremes, he said. This metadata codes global choices, such as black level and peak brightness, along with the dynamic parameters that change from scene to scene, he said. Philips compares the coding to describing position settings for audio fader controls, he said.

The metadata instructions require a worst-case maximum additional bandwidth of 10 kbps, and on average 1 kbps, Talstra said. The instructions are sufficient to tell a matching decoder how to display the pictures on screens with any brightness between the 100-nit and 5,000-nit grading extremes, he said. The metadata is easily carried by HDMI cable, but new HDMI protocols will probably be needed, he said. "One of the two grading passes can be much simpler than the other," said Talstra. "The dust has not yet settled on whether it is best to do the hard work on the HDR grade and then trim for LDR, or grade for LDR and then trim for HDR."

LDR is treated as extremely low HDR, but options are still open on how best to cope with LDR display of HDR content. Talstra said. A 10-bit HDR signal with metadata may be transmitted for direct feed to an HDR display, and down-converted to 8 bits for display on legacy LDR equipment, or an LDR signal with metadata can be transmitted for direct feed to a legacy TV, and then upconverted to HDR, he said.

Talstra and his team gave us wide-ranging demonstrations of variously graded still and movie source material, streamed with 10 bit, 4:2:0 coding in H.264 at Blu-ray data rates of about 20 Mbps. This was variously processed in real time by field programmable gate array (FPGA) circuitry and simultaneously displayed on the SIM2 monitor at 5,000 nits and a commercially available Sony 65-inch 4K Bravia LCD TV with extended brightness at around 800 nits.

The HDR signal on the SIM2 monitor showed detail in shadows alongside highlights such as torchlight spots. Our takeaway was that discerning viewers will appreciate the effect. For undiscerning viewers, switching on HDR may appear to lower overall brightness and switching off HDR may give the effect of raising the overall brightness by washing out colors. Careful choice of demonstration material under the right viewing conditions may prove vital to effectively promoting HDR to consumers -- a challenge at the point of sale that has impeded consumer adoption of other technologies such as 3D TV. As with the Dolby Vision demonstrations we saw in Berlin, we noted in the Philips demos that extreme light hotspots, such as those of flashlights or car headlights, may discomfort some viewers.

Philips will not say whether it has signed any commercial licenses for TV manufacturers to adopt its HDR system. "We are talking to all the manufacturers, including TP Vision, of course," said Frederic Guillanneuf, director-Philips Group Innovation. "The studios are evaluating the plug-ins. But we don’t want to say anything at the moment because we don’t want to say the wrong thing. It is for them to announce what they want to announce."

As for why the Philips HDR system was not shown at IFA, "we have been concentrating on B2B [business-to-business] meetings," Guillanneuf said. "But the time is now right for us to become more visible and get across the message that we are offering a solution which needs less hardware complexity, and less bandwidth and is scalable for different displays." On its HDR system, Philips wants to announce "and demonstrate in partnership" with TV makers and studios, he said. "We were not on the show floor at IFA or IBC, but we were giving B2B demonstrations at IBC. And we are looking at CES."

Philips’ road map is to have an integrated system, based on FPGA, ready for January CES, Talstra said. By the second half of 2015, system-on-chip ICs will be ready for commercialization, he said. Philips calculates that with a 40 nanometer process, adding HDR functionality to an SoC will require at worst only about 0.4 square millimeters of extra silicon, he said. "As to hardware complexity, a lot depends on implementation details," and some SoC platforms "may already support" HDR technology without a significant hardware change, he said. "Philips is not a chip manufacturer, so it is hard for us to translate this into a dollar figure." As for the cost of licensing the system, that will be minimal, "in the tens of cents ballpark" per unit shipped, he said.