HDMI 2.1a Standard Will Feature Source-Based Tone Mapping

During a pre-CES briefing, the HDMI Licensing Administrator has revealed there is going to be a new version of the 2.1 standard.

There is a feature called Source-Based Tone Mapping (SBTM) set to improve and optimize the HDR experience. This technology requires source and target devices to support the new standard.
Reportedly, the SBTM will remarkably benefit PC and game uses, like multi windowed environments. Since the tone mapping will be controlled by the source device, it will allow different windows to display SDR or HDR optimized content simultaneously.


This technology is not developed to replace existing HDR technologies (like HDR10, HLG), TFTCental notes. The SBTM is actually made to enrich the HDR experience as it offers a broader range of optimizations for HDR-capable devices.
Recently, there was a lot of backlash for lack of response to fake ‘HDMI 2.1’ displays now emerging in the Chinese market. However, we now know that HDMI 2.1 features are not a requirement, manufacturers can now claim partial 2.1 support without actually supporting the technologies related to the standard.

Reports say that the references to HDMI 2.1a features can still be found through Google Cache but the website does not list the standard anymore. However, the reason for the lack of 2.1 references is not known.

Source-Based Tone Mapping (SBTM) is a new HDR feature that allows a portion of the HDR mapping to be performed by the Source device instead of the Display device. SBTM is especially useful in cases where HDR and SDR video or graphics are combined together into a single picture, such as picture-in-picture or a program guide with an integrated video window. SBTM also enables PCs and gaming devices to automatically produce an optimized HDR signal in order to maximize the utilization of the display’s HDR capabilities without manual user configuration of the Source device.

— HDMI.org