Emerging standards are making the best of existing pixels. Understand the principles of HDR, learn how to build workflows to simplify production, and deliver the highest quality HDR pictures possible.
The legacy gamma adopted in 709 and 240M has recently been supplanted by two more approaches to applying non-linearity to luminance, namely the Hybrid Log Gamma (HLG) system developed by the BBC and NHK and the Perceptive Quantizer (PQ) developed by Dolby.
Broadcasters are famous for adjusting to changing circumstances during live broadcasts without missing a beat. Live radio DJs roll with the punches. Live TV news reporters, newscast directors, engineers and technicians move or cut away as fast as possible. It comes with the territory and it’s in our DNA. The trick is to make surprises appear to be part of the show and carry on.
To date, the explanations of gamma that are seen mostly restrict themselves to the voltage or brightness domain and very little has been published about the effects of gamma in the frequency domain. This is a great pity, because analysis in the frequency domain produces interesting results.
It is unwise to pretend that gamma corrected signals can successfully be multiplied, added and subtracted in a matrix as if they represented linear light. Yet in television it is done all the time.
TV test and measurement gear and instrument solutions also facilitate remote production and monitoring.
Now the CRT is history, we have to justify the retention of gamma on its performance as a perceptual compression codec. That requires its effect on human vision to be considered.
In the wake of the pandemic, Telestream has used the restrictions imposed on virtually every equipment supplier over the past few months to innovate and focus on providing new features for its products that facilitate remote operation and automated quality control for enterprise-scale broadcast and media operations.
There are two components of gamma that have quite different purposes. One of them is always necessary because displays and their surroundings are never equally as bright as the original scene. The other one is a compression technique.