Pretty much any online explainer about high dynamic range TVs (HDR) is hobbled by a not-insignificant asterisk: if you're reading it online, your screen almost certainly can't convey the visual difference. HDR benefits from a full pipeline of newfangled tech to increase color gamut and luminance ranges on screens. In other words, they're brighter and more colorful—and most computer and phone screens can't convey that.

But as it turns out, there's a way, albeit a geeky one, to visually break down both the impact and issues of current-day HDR. As one enterprising gamer found out, the answer is tucked away into every single Xbox One console.

A thread on the renowned gaming forum ResetERA appeared on Thursday with a huge swath of heatmap images from modern HDR-compatible games, all posted by a user with the handle EvilBoris. And as he explains to Ars Technica, these images came about simply out of curiosity.

The heat (map) is on



























"I was personally interested in why my experience with HDR products has been so varied," Boris tells Ars via a forum direct message. The anonymous forum member, whose day job revolves around "eye and lens systems" for a tech-research firm (along with a serious photography habit), had been confused about why certain video games' HDR modes looked different from others. So he started importing saved screenshots taken using the Xbox One X's internal screenshot tool. Unlike the PlayStation 4 platform, Xbox One supports an export of its HDR metadata in an image format called JXR.

With this mix of basic images and metadata, Boris was able to extract "nit output," or the exact brightness setting, for every single pixel in an image. From there, he followed some guidance from an Unreal Engine 4 post about HDR resources and attempted to "filter an un-toned HDR image to accurately visualize the brightness of an HDR game (using the "HDR-10" protocol). That effort, combined with a custom gradient map he applied to images, allowed him to render the above heatmap images.

What do they represent, exactly? In short, they show the exact brightness instructions sent to HDR TV sets—and they show off which game studios do this in ways that look best on modern TV sets. As Boris points out in his public explainer post, HDR-10's metadata contains exact nit output values, not relative ones, that account for a luminance maximum of 10,000 nits. Meaning, every TV set will be told to render certain brightness levels by a 4K HDR Blu-ray or video game, regardless of whether the TV is capable of reaching that 10,000-nit brightness. (Current HDR-10 TVs translate these values in various, appropriate ways, which prevents any default "light crush" issues.)

The first cool thing about Boris' heatmaps is that they offer a clear, visual answer to "what does HDR do?" A flattened, "SDR" image appears next to each corresponding, crazy-looking heatmap image, so you can make out shapes, reflections, time of day, and other visual basics. Then, a peek at the heatmap, along with its color legend, clarifies how much brightness data is in each pixel. The blue end of the heatmap color scale indicates darkness. Standard brightness information for evenly lit primary video content typically sits in the 150-nit range, which is yellow in the heatmap. The kind of content you'd expect to be brighter in an HDR image appears as red (1,000 nits), violet (4,000 nits), and white (10,000 nits).

In some images, this is as simple as a shining sun appearing in the heatmap as a concentrated ball of violet and white data. In others, more subtle HDR impact can be seen in heatmap information such as snow reflections, peeks of brightness in otherwise gray skies, and glimmers of light off of "natural" substances like leather and foliage.





Perhaps more compelling is Boris' examination of how various games employ HDR-10. Harsher, less-balanced bursts of HDR data are revealed in games like Deus Ex: Mankind Divided and Monster Hunter World. (Deus Ex's issues can be mitigated with a brightness-level tweak in its settings menu, at least.) On the other end, further examination put the undercooked 2017 open-world game Agents of Mayhem at the top of Boris' list, while certain games' use of a luminance cap, particularly Rise of the Tomb Raider and Final Fantasy XV, pays off with more balanced bursts of light. (Assassin's Creed: Origins is lauded, as well, which isn't surprising. That Ubisoft game has previously been praised for its built-in HDR-optimization menus, which Boris points out.)

Head to ResetERA for more of Boris' examinations on the topic.

Listing image by EA / DICE / EvilBoris