Overview: Standards-based curves

Standards-based tone-mapping approaches relate brightness adaptation to defined signal conventions and processing methods.

The ITU methods and ST 2094-related processing topics below have particular definitions and implementation contexts. Comparing them starts with the signal assumptions and the operation being performed. The linked pages retain those scopes, including the libplacebo context of the ST 2094 entries, alongside their visible mapping examples.

• BT.2390
  The BT.2390 EETF uses a smooth highlight roll-off to adapt an HDR signal to a display with a smaller luminance range.

• BT.2446 Method A
  BT.2446 Method A defines a conversion between HDR and SDR that includes a shaped brightness mapping and associated color processing.

• ST 2094-10 tone mapping (libplacebo)
  libplacebo's ST 2094-10 mapper fits a brightness curve using source and target range information plus a selected adaptation point.

• ST 2094-40 tone mapping (libplacebo)
  libplacebo's ST 2094-40 mapper can use a metadata-defined Bézier curve and adapts it to the output display range.

References

• ITU-R Report BT.2390-11
• ITU-R Report BT.2446-1: HDR and SDR conversion methods
• SMPTE ST 2094-10:2021, Application #1
• SMPTE ST 2094-40:2016, Application #4