ColorBox In-Line Color and HDR/SDR Transform v1.0 36 www.aja.com
This is a licensable option and includes:
• SDR, PQ, and S-Log3 to HLG
• HLG to SDR and PQ
• Scene-light and Display-light conversions
• Utilizes 33 point Tetrahedral 3D LUT Interpolation
• Proc Amp and Color Corrector
• Full bypass node for 12G-SDI and HDMI v2.0
• Support for mathematical HLG HDR dynamic range mapping per ITU BT.2408
BBC HLG LUT Conversions
Description abbreviations:
SDR = Standard Dynamic Range
PQ = High Dynamic Range using Perceptual Quantization curve
HLG = High Dynamic Range using Hybrid Log Gamma curve
SR = Scene Referred
DR = Display Referred
UC = Up Conversion (inverse tone mapping)
P3 = RGB color space for digital movie projection
Table 2. BBC HLG LUT Convert to HLG, Detailed Information
BBC HLG LUT Name, Number
Description
SDR Scene > HLG, #4-1a
For use with most compact SDR cameras that approximate the BT.709 OETF with
a square root. BT.709 signals are directly-mapped into BT.2100 HLG at the BT.2408
signal levels using a scene-light conversion. The “look” of the original BT.709 content
is changed to match the subjective look of “native” BT.2100 HLG cameras. 100% SDR
signal is directly-mapped to 75% HLG (“HDR Reference White”). This LUT is intended
to be used with compact SDR cameras with a limited dynamic-range, so no highlight
“boost” is applied.
SDR Scene > HLG Strict, #4-2a
For use with compact SDR cameras that implement a strict BT.709 OETF. BT.709
signals are directly-mapped into BT.2100 HLG at the BT.2408 signal levels, using
a scene-light conversion. The “look” of the original BT.709 content is changed to
match the subjective look of “native” BT.2100 HLG cameras. 100% SDR signal is
mapped to 75% HLG (“HDR Reference White”). This LUT is intended to be used with
compact SDR cameras with a limited dynamic-range, so no highlight “boost” is
applied.
NOTE: Unlike BT.2100 HLG, SDR cameras that implement a strict BT.709 OETF tend to
crush detail in the shadows of a scene. Such detail will become more evident after
applying this conversion. It is often better to adjust the SDR camera’s native OETF to
approximate a square root (which provides a better match to HLG) and then use LUT
4-1 rather than this LUT.
SDR Scene UpMap > HLG, #6-1a
For use with SDR cameras that approximate the BT.709 OETF with a square root.
BT.709 signals are up-mapped (inverse tone-mapped) to BT.2100 HLG, using a scene-
light conversion. The “look” of the original BT.709 content is changed to match the
“look” of native BT.2100 HLG cameras. While the ITU-R BT.2408 signal levels are taken
into account, a small boost is applied to the SDR highlights so that there is a close
match to natively produced HDR content. 100% SDR signal is up-mapped to 79%
HLG. 105% SDR signals (EBU R.103 “preferred range” signals) are up-mapped to 83%
HLG.