Part I: Introduction
It might come as a shock to some, but if we’re not enjoying 100% of the promise of HDR at home, it may not be entirely the fault of the televisions themselves. Flagship OLED TVs are fast approaching 1,000 nit peak brightness alongside 100% deadly accuracy of the P3 color space that most production houses grade to. Changes to the composition of the OLED compound allow a 20% increase in peak brightness in LG’s EVO panels. Larger heat sinks enable greater brightness while dramatically reducing image retention and the likelihood of burn-in. Sony flagship televisions are employing algorithms that boost the saturation of bright colors, overcoming one of the chief complaints of WRGB panels, that is, saturation taking a hit beyond 400 nits due to white sub-pixels.
Yet, in spite of these notable improvements, the industry practices we outlined in Why HDR Production Monitors Matter – shows that continue to be lit in an SDR environment, that continue to be monitored in SDR while the very first time anyone sees the footage on an HDR display is not infrequently months later in the grading suite, along with the regrettable decision in post to constrain the levels in the HDR pass to maintain consistency with the SDR version – all conspire to undermine the quality of HDR content for a long time to come. As a matter of fact, many of us are watching shows on displays that are leagues better than the ones found on 99% of sets!
Two recurring complaints of HDR by home theater enthusiasts are 24p judder and pictures that are too dark. Judder makes the picture look jerky, particularly in panning shots – but paradoxically, the higher contrast and brightness of today’s HDR televisions that contribute substantially to making the viewing experience so thrilling also exaggerate motion artifacts to the point of making some content all but unwatchable. Black frame insertion (BFI), used on TVs to reduce judder, makes the picture noticeably darker.
In this series, we’ll be describing the conditions responsible for 24p judder; how HDR exacerbates motion artifacts and how colorists are dealing with it; ways to reduce judder during acquisition; and innovative approaches to manipulating motion in post production. Note that we don’t want to eliminate judder entirely: judder has been around since the dawn of film and could even be said to constitute an essential component of the vocabulary of cinema; and even worse than judder is the motion smoothing feature in television sets responsible for the soap opera effect (SOE). But before diving in, let’s first examine the five pillars of image quality: color gamut, temporal resolution, quantization, spatial resolution and contrast.