Standard Dynamic Range

Standard Dynamic Range (SDR) is the collective term for the brightness encoding, production, and display systems used in traditional television and digital video, defined in relation to high dynamic range video. SDR is not a single resolution or codec; standard-definition, high-definition, and even ultra-high-definition images can all be SDR.

Traditional television transfer characteristics derive from CRT electro-optical response; digital production usually maps scene brightness to a limited signal range through gamma or piecewise functions. High-definition SDR often combines ITU-R BT.709 chromaticity primaries and transfer specifications; standard-definition digital television often uses BT.601. BT.1886 later provided clearer recommendations for reference-monitor electro-optical conversion. SDR content has no absolute peak brightness guaranteed automatically by the format. Production environments often center on reference white around 100 cd/m² and controlled dark-room monitoring, but consumer displays may present at higher or lower brightness and adjust gamma, black level, and tone by picture mode. Signal level, display brightness, and scene luminance must not be treated as the same quantity.

SDR and BT.709 are not synonyms. BT.709 covers HD image format, color parameters, and transfer characteristics; SDR may use other primaries, resolutions, and encapsulation. When media info shows only BT.709, it usually indicates a color tag but cannot guarantee the master was strictly produced for a reference environment.

Converting HDR to SDR requires tone mapping to compress a wider brightness and color volume into the target range. Simple clipping loses highlight and saturated detail; production-grade conversion must also handle reference white, graphics, skin tones, and local contrast. Putting SDR into an HDR container does not create highlight information that was not originally present.