DYNAMIC HDR ENHANCER Posted on June 5, 2021 By Phil Jones Dynamic HDR Enhancer increases overall screen brightness of HDR content while delivering rich colors and maintaining highlight detail Sony 4K Home Theater projectors introduced in 2020 and 2021 have a new feature called Dynamic HDR Enhancer. By utilizing a version of Sony’s X1 processor optimized for projection, these are the first Sony projectors that are able to analyze HDR content frame by frame for precise dynamic tone mapping of HDR10 content. There is a variety of information embedded in HDR content that an HDR display uses to make picture adjustments. First, there is an HDR Infoframe which tells the video display to switch to the appropriate HDR mode. Next, is metadata which a display can use to help tone map HDR content. The two pieces of metadata that the projector’s video processor uses for HDR tone mapping are: MaxFALL (Maximum Frame–Average Light Level) average brightness of the brightest frame in the entire clip. Authoring guidelines state that this should not exceed 400 nits.MaxCLL (The Maximum Content Light Level) which is the brightest pixel in the entire clip. The average brightness of most HDR video frames is usually much less than 400 nits with a few peak highlights (sparks, flame tips, reflections) reaching up to 10,000 nits. Let’s discuss why tone mapping is needed. HDR consumer content (4K Blu-ray and streaming) is mastered for playback on a flat panel, not a projector, so it’s produced at a variety of brightness levels ranging from 1,000 nits (292 fL) to 4,000 (1167fL) nits. Most 4K HDR capable projectors can only deliver between 100 nits (29fL) and 200 nits (58 fL). This means no HDR compatible home theater projector can reproduce all the brightness found in consumer HDR content. As a result, HDR projectors utilize tone mapping which is a compromise between maintaining bright highlight details and delivering full screen brightness. When the HDR info frame is detected, most HDR projectors switch to HDR mode with a fixed tone map. This one-size-fits-all approach can hurt HDR performance. Last year, projector companies introduced projectors with auto tone mapping to automatically adjust a projector’s HDR settings (tone mapping curves) to try to optimize HDR10 image quality. The goal was to better utilize the projector’s brightness capabilities based on the HDR content being shown. Since the MaxFALL/MaxCLL metadata is based on the average brightness of the brightest frame and brightest pixel in the movie, certain scenes with lower than average frame levels can still look way too dark. In many cases, the metadata is missing or incorrect so the projector might not have the right information to work with. Also, since the same embedded metadata (MaxCLL/MaxFALL) is applied throughout the entire movie, sometimes the tone mapping decisions made by the projector can be a little off. Higher-end LCD and OLED TVs have been able to measure the HDR content frame-by-frame to generate accurate metadata dynamically for years. In 2020, Sony added that capability to their projectors as well. Unlike other projector manufacturers, Sony leverages years of experience with HDR tone mapping since Sony 4K TVs have had the capability since 2017. The new “X1 for Projectors” processor not only improves detail and resolution, it also made a noticeable improvement in the Sony HDR performance compared to previous models. HDR content is brighter, colors are richer, black levels are deeper, and bright highlight detail is visible. Sony VW915ES Dynamic HDR Enhancer When watching HDR content, sometimes brighter highlights will still be clipped but Sony believes this is necessary to keep most of the onscreen image as close to the director’s intent as possible. You can adjust the tone mapping level using the HDR Contrast adjustment. There are 3 levels (LOW, MED, and HIGH). While reviewing Sony projectors with this feature, I left the setting on LOW most of the time with excellent results. Sony side-by-side of VW715ES vs VW695ES As an example of this enhanced HDR performance, during my review of the VW715ES, I took several photos of the new VW715ES and the predecessor model VW615ES side by side on the same screen. As you can see from the image above, Dynamic HDR Enhancer powered by the X1 processor makes a noticeable improvement in Sony HDR performance compared to the previous Sony projector. While it is difficult to capture all the differences in a photo, you can see that the newer model has brighter HDR content, more vibrant color, and deeper black levels, while still maintaining brighter highlight detail. It is worth noting that since HLG is based on a Gamma curve just like SDR, it does not need to be tone mapped by the projector.