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Beyond HD

 

More pixels, more images, more colours. Ultra-HD, the television of the future, aims to provide just that. In this context, the IRT intensively deals with issues of technology and standardization. 

 

Ultra-HD not only represents increased resolution (4 times HD resolution) but also an extension of the colour space (Wider Color Gamut WCG), the contrast range (High Dynamic Range HDR), and an increase in the video frame rate (Higher Frame Rate HFR) – it is about “not just more, but better pixels”. This opinion is above all represented by the public broadcasting companies in Germany and Europe. Current TV sets already support some UHD features (especially the higher resolution), but not yet as a total package.

High Dynamic Range (HDR)

 

When speaking of HDR, it is – to put it simply – about the representation of an extended contrast range that approaches the human sense of sight. Impressively realistic images that we are familiar with from photography can now also be created with video. Until just a few years ago neither the camera technology nor playback devices were able to accomplish this. Today’s (above all digital cinema) cameras can capture the required dynamic range (c. 13-14 f-stops) and thus form the foundation for HDR. The standardisation committees mainly discuss two approaches to HDR for broadcast operations. The specifications of the UHD-compatible Blu-ray disc were published in mid-2015 and are already committed to the PQ (Perceptual Quantizer) approach based on SMPTE ST2084. The first TV sets supporting HDR in a standardised form are now successively coming to market. For playback on traditional devices, however, a conversion of the signal is required. The second approach, which was developed in cooperation between BBC and NHK, is called Hybrid Log Gamma. The advantage of this modified gamma curve is that both traditional and HDR-compatible television sets can process the signal and display the image without the need for conversion. The decision about which approach will win in the end will be made in the coming months.

High Frame Rate (HFR)

 

In addition to the local resolution (more pixels per area), the video resolution (more frames per second) also plays a big role in television. In sports this becomes especially evident if the camera turns – details are actually sharper due to higher local resolution, but sharpness is lost due to the camera movement: they “smear”. An interframe calculation in end devices, as many flat screens do today, or an increase in the number of images or frames while recording can remedy this problem. A higher frame rate, however, also implies a higher bandwidth on the production side and in display processing. The IRT again dealt with this issue and conducted more research. Along with the confirmation of the results generated in 2013 (see 2013 Annual Report), tests were expanded with an interframe calculation in connection with various shutter times and the later HEVC encoding, aiming to answer the question about how big the data rate overhead would be if HRF (native or calculated) is transmitted to the viewer. It turned out that a doubling of the frames per second does not equal a doubling of the data rate; it increases (depending on video content) only by approximately 20%.

Your contacts

Sebastian Goossens
Sachgebietsleiter
Head of Department
Tel. +49 (0)89 32399-358