Published 9/1/2021

When viewers sit about nine feet from their TV screensconsidered the average viewing distancea 1080p60 Full HD picture enhanced with High Dynamic Range (HDR) makes a greater impression on them than an Ultra High-Definition (UHD) picture with only Standard Dynamic Range (SDR). As we discussed in our previous blog, when people compare the visual attributes of HDR and SDR pictures, whether in HD or UHD resolution, they usually prefer the look of HD-HDR.

This is because HDR brings out greater detail in the darkest corners and brightest areas of the picture. There is also the perception of increased contrast, sharper textures, and more vivid, saturated colors. Since HDR was developed as an end-to-end system, the video must be captured, processed, and delivered in an HDR compliant manner, and viewers must display it on an HDR-capable TV set to appreciate this superior picture quality.

On the production side, shooting full 1080p60 HD video with HDR makes more sense for both live telecasts and recorded masters than shooting at UHDs nearly 4K resolution without HDR. Considering the whole workflow, including acquisition, storage, editing, processing, and transmission, uncompressed UHD/4K video can be much more costly to produce than HD-HDR because the UHD signal contains a higher data rate due to the larger volume of pixels and higher resolution. To lower the data rate and production costs, its possible to down-convert to Full HD, but that reduces image quality.

So, in a world where bits are bucks, why not broadcast and master in the more cost-efficient HD-HDR format? Considering that viewers prefer the look of HD-HDR, broadcast and production professionals get a bigger bang for the buck with HD-HDR. For large-scale live events, all video sources can be converted to the same HD-HDR format at the input of the production switcher. The output of the switcher is called an HDR single master. The show can be output in 1080p60 HDR, or simultaneously in SDR. From that HDR single master, all formats can be created as necessary for broadcast, streaming, and mastering.

But, since HDR and SDR video have fundamentally different looks, HD-HDR video must be captured, processed, and converted to SDR properly so that it looks good on a SDR TV. To understand the challenges of HDR format conversion, lets first consider the most popular HDR profiles in use today:

• HDR10 (10-bit) is available in most 4K HDR TVs. Its the most commonly used format by TV manufacturers today. Its a free, open standard.
• HDR10+ is similar to HDR10, except that it adds dynamic metadata developed by Samsung.
• HLG10 Hybrid Log Gamma 10-bit, which is available in newer HDR HDTVs, was developed by the BBC and NHK for live broadcast TV.
• Dolby Vision -SMPTE ST2084 (12 bit) is a proprietary format that Dolby Laboratories created for movie post production, and it uses metadata. It requires a Dolby a royalty fee to use it.

Were likely to see a hybrid world where these leading HDR formats remain in use alongside SDR for the foreseeable future. So, managing HDR format conversion in a way that looks good on both HDR and SDR TVs will be important for some time to come. In the simplest terms, the HDR signal is converted to SDR by applying an inverse gamma curve making the signal flat or linear, then applying a BT.709 standard gamma curve to it.

For HDR and SDR camera shading, video shaders should adjust the picture for the SDR image. If the SDR picture is shaded correctly, it will convert well to HDR since HDR exceeds the SDR range. Whereas, shading for only HDR could clip the SDR picture. The best way for camera shaders to monitor HDR and SDR imagery is by using a monitor with false color capability that essentially displays color differences between the two.

At Hitachi Kokusai, weve simplified this complex HDR conversion process by designing camera control units (CCUs) capable of outputting the 1080p60 Full HD signal as HDR and SDR simultaneously, with individual adjustments. An optional UHD HDR up-conversion is also available. We offer top-of-the-line, low noise camera systems, such as the CMOS Global Shutter SK-HD1800 for studio and/or field use, which fully support both HDR and SDR natively.

To learn more about HDR innovations and tips from Hitachi Kokusai, check out our Short Takes video on HDR, as well as other videos touching on HDR in our online Video Gallery. When it comes to High Dynamic Range, our goal is to ensure the highest Quality of Experience (QoE) for those viewing HDR video content.