SDR (Standard Dynamic Range)

SDR (Standard Dynamic Range) is the historical and still-dominant video specification, defined by Rec.709 for HD and Rec.601 for SD, with peak luminance assumed at 100 nits, gamma 2.4 transfer function (BT.1886), and Rec.709 color primaries. SDR predates the HDR era and remains the delivery target for the vast majority of streaming, broadcast and physical media — Netflix's standard tier, YouTube's default playback, all broadcast television (excepting HDR-enabled streams) and almost all theatrical projection use SDR specs in their final delivery. The 100-nit peak luminance corresponds to the cathode-ray tube reference brightness of the broadcast television era, intentionally low to suit dim viewing environments. SDR's 8-bit encoding (with optional 10-bit for higher-end broadcast) provides about 6-7 stops of usable dynamic range before clipping or crushing, far below the 13-14 stops modern cinema cameras can capture. Color grading SDR requires aggressive tonal compression of camera log data — bright highlights (windows, lights) typically clip or roll off, deep shadows compress. SDR remains the safe deliverable for content that needs to play anywhere, and most HDR-mastered productions ship an SDR 'trim' alongside the HDR master for SDR-only viewers. SDR is not deprecated and will coexist with HDR formats for years to come. Reference: ITU-R BT.709-6, ITU-R BT.1886.