IEC 61966-2-1:1999/AMD1:2003

Amendment 1 - Multimedia systems and equipment - Colour measurement and management - Part 2-1: Colour management - Default RGB colour space - sRGB

General Information

• Status: Published
• Publication Date: 22-Jan-2003
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.160.60 - Multimedia systems and teleconferencing equipment
• ICS: 37.080 - Document imaging applications
• Technical Committee: TC 100 - Audio, video and multimedia systems and equipment
• Current Stage: PPUB - Publication issued
• Start Date: 28-Feb-2003
• Completion Date: 23-Jan-2003

Relations

• Amends: IEC 61966-2-1:1999 - Multimedia systems and equipment - Colour measurement and management - Part 2-1: Colour management - Default RGB colour space - sRGB
• Effective Date: 05-Sep-2023

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD
61966-2-1
1999
AMENDMENT 1
2003-01
Amendment 1
Multimedia systems and equipment –
Colour measurement and management –
Part 2-1:
Colour management –
Default RGB colour space - sRGB
Amendement 1
Mesure et gestion de la couleur dans les systèmes
et appareils multimédia –
Partie 2-1:
Gestion de la couleur –
Espace chromatique RVB par défaut - sRVB
 IEC 2003 Droits de reproduction réservés  Copyright - all rights reserved
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PRICE CODE
P
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– 2 – 61966-2–1 Amend. 1  IEC:2003(E)
FOREWORD
This amendment has been prepared by Technical Area 2: Colour measurement and
management, of IEC technical committee 100: Audio, video and multimedia systems
and equipment and ISO TC 42: Photography.
The text of this amendment is based on the following documents:
FDIS Report on voting
100/555A/FDIS 100/625/RVD
Full information on the voting for the approval of this amendment can be found in the report on
voting indicated in the above table.
It is published as a double logo standard.
In the ISO the Standard has been approved by 10 P-members out of 10 having cast the vote.
_____________
Page 5
CONTENTS
Add the titles of Annexes F, G and H as follows:
Annex F (normative) Default YCC encoding transformation for a standard luma-chroma-
chroma colour space: sYCC
Annex G (informative) Extended gamut encoding for sRGB: bg-sRGB and its YCC
transformation: bg-sYCC
Annex H (informative) CIELAB (L*a*b*) transformation
Page 49
Add the following new Annexes F, G and H after Annex E:

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61966-2–1 Amend. 1  IEC:2003(E) – 3 –
Annex F
(normative)
Default YCC encoding transformation for a
standard luma-chroma-chroma colour space: sYCC
The method of digitization in this annex is designed to complement current sRGB-based colour
management strategies by explicitly standardizing a default transformation between sRGB and
a standard luma-chroma-chroma colour space (sYCC). Application and hardware developers
who want to support various colour compression schemes based on luma-chroma-chroma
spaces can utilize this annex. Since this sYCC colour space is a simple extension of the sRGB
colour space as defined in this standard, the same reference conditions are shared by both
colour spaces.
F.1 General
The encoding transformations between sYCC values and CIE 1931 XYZ values provide
unambiguous methods to represent optimum image colorimetry when viewed on a hypothetical
reference display that is capable of producing all colours defined by sYCC encoding, in the
reference viewing conditions by the reference observer. Non-linear floating point sR′G′B′
represent the appearance of the image as displayed on the reference display in the reference
viewing condition described in Clause 4 of this standard.
F.2 Transformation from sYCC values ( Y , Cb , Cr ) to CIE 1931 XYZ
sYCC sYCC sYCC
values
The non-linear sY′C ′C′ values can be computed using the following relationship:
b r
′
Y =()Y − KDC(WDC − KDC)
sYCC sYCC
′ (F.1)
Cb =()Cb − Offset Range
sYCC sYCC
Cr′ =()Cr − Offset Range
sYCC sYCC
For 24-bit encoding (8-bit/channel), WDC = 255, KDC = 0, Range = 255, and Offset = 128, and
the relationship is defined as;
′
Y = (Y − 0)()255 − 0 = Y 255
sYCC sYCC sYCC
(8) (8)
Cb′ =()Cb −128 255 (F.2)
sYCC sYCC
(8)
′
Cr =()Cr −128 255
sYCC sYCC
(8)
24-bit encoding (8-bit/channel) shall be the default sYCC encoding bit depth. Other bit depths
may be unsupported for general use.
Where other N-bit/channel encoding is supported ( N > 8), the relationship is defined as;

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– 4 – 61966-2–1 Amend. 1  IEC:2003(E)
N
′
Y = Y (2 −1)
sYCC sYCC
(N)
N −1 N
Cb′ =()Cb − 2 ()2 −1 (F.2′)
sYCC sYCC
(N)
N −1 N
′
Cr =()Cr − 2 ()2 −1
sYCC sYCC
(N)
For 24-bit encoding (8-bit/channel), the non-linear sY′C ′C′ values are transformed to the non-
b r
linear sR′G′B′ values as follows;
R′ 1,000 0 0,000 0 1,402 0 Y ′
    
sRGB sYCC
    
′ ′
G = 1,000 0 − 0,344 1 − 0,714 1 Cb (F.3)
sRGB sYCC
    
 ′    ′ 
B 1,000 0 1,772 0 0,000 0 Cr
 sRGB   sYCC
For N-bit/channel encoding ( N > 8), it is recommended to replace the matrix coefficients in the
equation F.3 with the coefficients of the inverse matrix of the equation F.12 with enough
accuracy decimal points. For example, following matrix with 6 decimal points has enough
accuracy for the case of 16-bit/channel.
R′ 1,000 000 0,000 037 1,401 988 Y ′
    
sRGB sYCC
    
′ ′
G = 1,000 000 − 0,344 113 − 0,714 104 Cb (F.3′)
sRGB sYCC
    
    
B′ 1,000 000 1,771 978 0,000 135 Cr′
sRGB sYCC
    
The non-linear sR′G′B′ values are then transformed to CIE 1931 XYZ values as follows:
′ ′ ′
If R
...