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Colorimetric characteristics of ultra-high definition digital television (UHDTV) systems

Colorimetric characteristics of ultra-high definition digital television systems are presented in Table 3.7. In Recommendation ITU-R BT.2020 [3.10] a newly proposed signal format for UHDTV systems is specified. For UHDTV systems 10 bit and 12 bit coded representation is used and decimal values of the quantized signals are:

‒ for gamma-corrected signals:

(3.30)

(3.31)

(3.32)

‒ for luminance and colour difference signals:

Constant luminance (CL):

(3.33)

(3.34)

(3.35)

Non-Constant luminance (NCL):

(3.36)

(3.37)

(3.38)

 


TABLE 3.4
Digital encoding equations (Recommendation ITU-R BT.1361)

Parameter Equations
  Conventional color gamut system Extended color gamut system(1)
Quantization of RGB, luminance and color-difference signals (2) (3)
Derivation of luminance and color-difference signals via quantized RGB signals(4)
(1) A detailed explanation is given in Annex 1 of Recommendation ITU-R BT.1361 [3.6]. (2) “n” denotes the number of the bit-length of the quantized signal. (3) The operator INT returns the value of 0 for fractional parts in the range of 0 to 0.4999... and +1 for fractional parts in the range of 0.5 to 0.9999..., i.e. it rounds up fractions above 0.5. (4) Annex 2 of Recommendation ITU-R BT.1361 [3.6] specifies a procedure to obtain optimized integer coefficients for digital implementation.

 


TABLE 3.5
Optimized integer coefficients for conventional color gamut system
(Recommendation ITU-R BT.1361)

Coeff. bits Denominator Luminance Y Color-difference CB Color-difference CR
m 2m
19 –30 –101 –119 –12
–60 –202 –238 –24
1 024 –120 –404 –476 –48
2 048 1 465 –240 –807 1 047 1 047 –951 –96
4 096 2 929 –480 –1 615 2 095 2 095 –1 903 –192
8 192 1 742 5 859 –960 –3 230 4 190 4 189 –3 805 –384
16 384 3 483 11 718 1 183 –1 920 –6 459 8 379 8 379 –7 611 –768
32 768 6 966 23 436 2 366 –3 840 –12 918 16 758 16 758 –15 221 –1 537
65 536 13 933 46 871 4 732 –7 680 –25 836 33 516 33 516 –30 443 –3 073
Note 3 – For the conventional color gamut system, the RGB signal region used in the optimization is the nominal signal range of Recommendation ITU-R BT.601 and its extensions, i.e. the range 16  2n–8– 235  2n–8for an n-bit system. For the extended color gamut system, it is the maximum signal range of Recommendation ITU-R BT.601 and its extensions, i.e. 1  2 n–8– 254  2 n–8.

 



TABLE 3.6
Optimized integer coefficients for extended color gamut system
(Recommendation ITU-R BT.1361)

Coeff. bits Denominator Luminance Y Color-difference CB Color-difference CR
m 2m
–12 723 –41 –138 –163 –16
–50 893 –82 –276 –325 –33
1 024 1 003 –203 571 –164 –553 –651 –66
2 048 2 005 –814 285 –329 –1 105 1 434 1 434 –1 302 –132
4 096 1 192 4 009 –3 257 139 –657 –2 210 2 867 2 867 –2 604 –263
8 192 2 384 8 019 –13 028 557 –1 314 –4 420 5 734 5 734 –5 208 –526
16 384 4 768 16 039 1 619 –52 114 227 –2 628 –8 841 11 469 11 469 –10 417 –1 052
32 768 9 535 32 078 3 238 –208 456 909 –5 256 –17 682 22 938 22 937 –20 834 –2 103
65 536 19 071 64 155 6 476 –833 827 635 –10 512 –35 363 45 875 45 875 –41 669 –4 206
The value of depends on the signal bit-lengths n, and the values listed are those for the cases m = n. It is confirmed that the optimized values are identical with the initial nearest integers in m + n bits precision, when m and n are within 8‒16.

 


 

TABLE 3.7
Colorimetric characteristics of ultra-high definition digital television systems

System Primaries and reference white chromaticity coordinates Opto-electronic and electro–optic conversion characteristics Coding equation
UHDTV       Opto-electronic conversion: where E is voltage normalized by the reference white level and proportional to the implicit light intensity that would be detected with a reference camera colour channel R, G, B; E' is the resulting non-linear signal. α = 1.099 and β = 0.018 for 10-bit system α = 1.0993 and β = 0.0181 for 12-bit system Constant luminance : Non-constant luminance :
  x y
Red 0.708 0.292
Green 0.170 0.797
Blue 0.131 0.046
White D65 0.3127 0.3290
 

 



Date: 2014-12-22; view: 960


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