Converting SDR to HDR and back again is becoming essential for broadcasters – but without the right tools, it can get pretty messy
arlier this year, EVS acquired broadcast and media network infrastructure specialist Axon Digital Design. It was the company’s biggest acquisition ever and positioned EVS to be able to provide a comprehensive media infrastructure
round trips. “When you convert a source from SDR to HDR, you’re going from a small space to a big space and it forgives errors,” explains Schut. “But going back is more difficult – you’re taking something big and you have to put it into a smaller dynamic range.” Live sports is an arena where HDR really shines. Areas of a football field that might be blown out by sun or too shady to see clearly are suddenly visible in HDR’s wider dynamic range and bigger colour space. But while events may be shot and produced in HDR, most of the home audience is still watching on SDR TVs. The final output needs to be converted from HDR for an SDR playout. This HDR to SDR final conversion is something that requires a bit of care. Like an artist mixing paints, it’s easy to turn pure white into gray, but turning grey back into white is an uphill battle. A football match may be shot in HDR, but some of the cameras – the goal cam, for example – will likely just be an SDR camera. That camera source needs to be converted to match the rest of the HDR workflow and delivery, but will then – along with the rest of the feed – need to be converted again to the SDR playout.
solution that includes advanced IP processing, SDI/ IP conversion, SDN-based control and monitoring, as well as UHD 4K and IP multiviewer. Part of the expertise brought on board by the Axon acquisition will allow EVS to provide better high-dynamic range (HDR) video services, including the ability to easily convert standard dynamic range images to HDR and back. “We were fairly early adopters of HDR conversion,” explains Peter Schut, former Axon CTO and vice-president of R&D, now EVS’s senior vice-president of media infrastructure. Axon’s technologies for HDR conversion used LUTs (lookup tables), which provide a straightforward conversion from a given colour and brightness to the colour and brightness that is desired for the conversion. LUTs can be fairly complex, but they require some know-how and supervision to work well in multiple conversion
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