This useful Xbox Series X feature is hidden away for a good reason

techradar.com:

A secret Xbox Series X feature that lets you see the exact number of nits your TV is outputting when in the console’s HDR calibration app has been discovered by a Reddit user.

If you’re familiar with the HDR calibration app on Xbox consoles, you’ll already know that you’re presented with a series of checkerboard patterns and asked to make the screen brighter or darker until the squares look the same. 

This ensures that you’re getting the deepest blacks possible and highlights won’t be blown out when playing in HDR, especially if you use HGiG (HDR Gaming Interest Group). That lets your console tone map HDR and bypasses your TV from tone mapping the calibrated image for a second time.

It’s important that you get the most accurate values possible when using the HDR calibration app, then, but depending on the lighting in your room and how you perceive the checkerboard patterns, this isn’t always possible. However, thanks to this trick discovered by Reddit user MazharulAlam, you can see the exact numbers your Xbox is outputting by pressing all the rear buttons (LB+RB+LT+RT) on the Xbox Wireless Controller while in the HDR calibration app. 

Seeing the exact numbers onscreen means users can make finer adjustments to the HDR output. For example, you’ll want your Xbox to display a value of zero when adjusting the dark checkerboard images to ensure you’re getting perfect blacks.

If you’re confused about what MaxFFTML, MaxTML, and MinTML mean, u/MazharuAlam provided an explanation in the same Reddit thread. MaxFFTML stands for ‘Max Full Frame Tone Map Luminance’ and is the maximum luminance at which your display can show white detail on a full screen. MaxTML stands for ‘Max Tone Map Lumiance’ and is the maximum luminance at which your