GRASS VALLEY XIP-3901, Руководство пользователя

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302
BBC HLG Look-Up Table
Extending the SDR Color Gamut
Extending the SDR Color Gamut
When matching SDR BT.709 cameras with BT.2100 HLG cameras, significantly better results
can be obtained if the signal clippers on the SDR cameras are relaxed to EBU Technical
Recommendation R103 signal levels (5%/+105%) and the conversion process takes account
of the signals in the sub-blacks and super-whites. The sub-black and super-white signals
produced by many cameras effectively increase the dynamic range and color gamut of the
camera. More details can be found in ITU-R report BT.2250.
In order to exploit the extended SDR signal range, the conversion LUT has to operate in
“full-range” mode, taking account of the black level offset of the SDR input signals (10-bit
code value 64) (LUT Type III). Because of the improved performance, the scene-referred
BT.709 to BT.2100 HLG direct mapping LUT (LUT 4) and up-mapping LUTs (LUT 6-1 and 6-2),
are only provided in full-range mode (Type III) versions.
Output Signal Clipping
Type III LUTs with SDR BT.709 outputs are clipped within the look-up table to EBU Technical
Recommendation R103 signal levels. In territories with stricter limits on the SDR signal
range, an additional hardware legalizer may be needed.
The remaining Type II and Type III LUTs with PQ or HLG outputs are clipped to full-range, to
ensure that they pass ITU-R BT.2111 HDR Color Bars. External processing, illustrated in Type
II signal scaling, intended for full-range input signals (for example, S-Log3) , on page 300
and Type III signal scaling, primarily intended for hardware-based LUT applications , on
page 300, is necessary to clip the LUT output to 10-bit SDI range (4 to 1019).
Camer
a t
o
SDR shading
HDR only camera 8 or 12
  
G
raphics
SDR matching color
branding
3
 
SDR matching in-
vision signage
4
 
Pr
ogr
am
O
utput
SDR complete 8
 
SDR “Clean Feed” for
mixing with unilateral
12
 
PQ for onward 7
 