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: 1490