From Wikipedia, the free encyclopedia
Colour space used in the SECAM analog color TV standard
An image along with its
Y
{\displaystyle Y}
,
D
B
{\displaystyle D_{B}}
and
D
R
{\displaystyle D_{R}}
components.
YDbDr , sometimes written
Y
D
B
D
R
{\displaystyle YD_{B}D_{R}}
, is the colour space [ 1] used in the SECAM (adopted in France and some countries of the former Eastern Bloc ) analog colour television broadcasting standard.[ 2] [ 3] [ 4] It is very close to YUV (used on the PAL system) and its related colour spaces such as YIQ (used on the NTSC system), YPbPr and YCbCr .[ 5] [ 6]
Y
D
B
D
R
{\displaystyle YD_{B}D_{R}}
is composed of three components:
Y
{\displaystyle Y}
,
D
B
{\displaystyle D_{B}}
and
D
R
{\displaystyle D_{R}}
.
Y
{\displaystyle Y}
is the luminance ,
D
B
{\displaystyle D_{B}}
and
D
R
{\displaystyle D_{R}}
are the chrominance components, representing the red and blue colour differences .[ 7]
The three component signals are created from an original
R
G
B
{\displaystyle RGB}
(red, green and blue) source. The weighted values of
R
{\displaystyle R}
,
G
{\displaystyle G}
and
B
{\displaystyle B}
are added together to produce a single
Y
{\displaystyle Y}
signal, representing the overall brightness, or luminance, of that spot. The
D
B
{\displaystyle D_{B}}
signal is then created by subtracting the
Y
{\displaystyle Y}
from the blue signal of the original
R
G
B
{\displaystyle RGB}
, and then scaling; and
D
R
{\displaystyle D_{R}}
by subtracting the
Y
{\displaystyle Y}
from the red, and then scaling by a different factor.
These formulae approximate the conversion between the RGB colour space and
Y
D
B
D
R
{\displaystyle YD_{B}D_{R}}
.
R
,
G
,
B
,
Y
∈
[
0
,
1
]
D
B
,
D
R
∈
[
−
1.333
,
1.333
]
{\displaystyle {\begin{aligned}R,G,B,Y&\in \left[0,1\right]\\D_{B},D_{R}&\in \left[-1.333,1.333\right]\end{aligned}}}
From RGB to YDbDr:
Y
=
0.299
R
0.587
G
0.114
B
D
B
=
−
0.450
R
−
0.883
G
1.333
B
D
R
=
−
1.333
R
1.116
G
0.217
B
[
Y
D
B
D
R
]
=
[
0.299
0.587
0.114
−
0.450
−
0.883
1.333
−
1.333
1.116
0.217
]
[
R
G
B
]
{\displaystyle {\begin{aligned}Y&= 0.299R 0.587G 0.114B\\D_{B}&=-0.450R-0.883G 1.333B\\D_{R}&=-1.333R 1.116G 0.217B\\{\begin{bmatrix}Y\\D_{B}\\D_{R}\end{bmatrix}}&={\begin{bmatrix}0.299&0.587&0.114\\-0.450&-0.883&1.333\\-1.333&1.116&0.217\end{bmatrix}}{\begin{bmatrix}R\\G\\B\end{bmatrix}}\end{aligned}}}
From YDbDr to RGB:
R
=
Y
0.000092303716148
D
B
−
0.525912630661865
D
R
G
=
Y
−
0.129132898890509
D
B
0.267899328207599
D
R
B
=
Y
0.664679059978955
D
B
−
0.000079202543533
D
R
[
R
G
B
]
=
[
1
0.000092303716148
−
0.525912630661865
1
−
0.129132898890509
0.267899328207599
1
0.664679059978955
−
0.000079202543533
]
[
Y
D
B
D
R
]
{\displaystyle {\begin{aligned}R&=Y 0.000092303716148D_{B}-0.525912630661865D_{R}\\G&=Y-0.129132898890509D_{B} 0.267899328207599D_{R}\\B&=Y 0.664679059978955D_{B}-0.000079202543533D_{R}\\{\begin{bmatrix}R\\G\\B\end{bmatrix}}&={\begin{bmatrix}1&0.000092303716148&-0.525912630661865\\1&-0.129132898890509&0.267899328207599\\1&0.664679059978955&-0.000079202543533\end{bmatrix}}{\begin{bmatrix}Y\\D_{B}\\D_{R}\end{bmatrix}}\end{aligned}}}
You may note that the
Y
{\displaystyle Y}
component of
Y
D
B
D
R
{\displaystyle YD_{B}D_{R}}
is the same as the
Y
{\displaystyle Y}
component of
Y
{\displaystyle Y}
U
{\displaystyle U}
V
{\displaystyle V}
.
D
B
{\displaystyle D_{B}}
and
D
R
{\displaystyle D_{R}}
are related to the
U
{\displaystyle U}
and
V
{\displaystyle V}
components of the YUV colour space as follows:
D
B
=
3.059
U
D
R
=
−
2.169
V
{\displaystyle {\begin{aligned}D_{B}&= 3.059U\\D_{R}&=-2.169V\end{aligned}}}
YUV - related colour system
^ Issues in Electronic Circuits, Devices, and Materials: 2011 Edition . ScholarlyEditions. 2012-01-09. p. 1146. ISBN 978-1-4649-6373-5 .
^ Recommendation ITU-R BT.470-6 - Conventional Television Systems (PDF) . ITU-R. 1998.
^ Shi, Yun-Qing; Sun, Huifang (2019-03-07). Image and Video Compression for Multimedia Engineering: Fundamentals, Algorithms, and Standards, Third Edition . CRC Press. ISBN 978-1-351-57864-6 .
^ Dorf, Richard C. (2018-10-03). Circuits, Signals, and Speech and Image Processing . CRC Press. ISBN 978-1-4200-0308-6 .
^ Hoang, Dzung Tien; Vitter, Jeffrey Scott (2002-02-21). Efficient Algorithms for MPEG Video Compression . Wiley. ISBN 978-0-471-37942-3 .
^ Shum, Heung-Yeung; Chan, Shing-Chow; Kang, Sing Bing (2008-05-26). Image-Based Rendering . Springer Science & Business Media. ISBN 978-0-387-32668-9 .
^ ASC, David Stump (2021-11-18). Digital Cinematography: Fundamentals, Tools, Techniques, and Workflows . Routledge. ISBN 978-0-429-88901-1 .
Shi, Yun Q. and Sun, Huifang Image and Video Compression for Multimedia Engineering , CRC Press, 2000 ISBN 0-8493-3491-8