YDbDr

YDbDr是SECAM制式規格電視所采用的色彩空間。

1966年法国提出SECAM彩色电视制式，並制度YDbDr。

公式

Y, Db和Dr訊號是產生自RGB 三原色。R, G和B的權重儲存於Y信号，所代表的是该点亮度.

RGB 色彩空间和YDbDr轉換之近似公式。

${\displaystyle R,G,B,Y\in \left[0,1\right]}$

${\displaystyle Db\in \left[-1.333,1.333\right]}$

${\displaystyle Dr\in \left[-1.333,1.333\right]}$

從RGB至YDbDr:

${\displaystyle Y=}$	${\displaystyle 0.299R}$	${\displaystyle +0.587G}$	${\displaystyle +0.114B}$
${\displaystyle Db=}$	${\displaystyle -0.450R}$	${\displaystyle -0.883G}$	${\displaystyle +1.333B}$
${\displaystyle Dr=}$	${\displaystyle -1.333R}$	${\displaystyle +1.116G}$	${\displaystyle +0.217B}$

从YDbDr至RGB:

${\displaystyle R=}$	${\displaystyle Y}$	${\displaystyle +0.000092303716148Db}$	${\displaystyle -0.525912630661865Dr}$
${\displaystyle G=}$	${\displaystyle Y}$	${\displaystyle -0.129132898890509Db}$	${\displaystyle +0.267899328207599Dr}$
${\displaystyle B=}$	${\displaystyle Y}$	${\displaystyle +0.664679059978955Db}$	${\displaystyle -0.000079202543533Dr}$

或者:

${\displaystyle {\begin{bmatrix}Y\\Db\\Dr\end{bmatrix}}={\begin{bmatrix}0.299&0.587&0.114\\-0.450&-0.883&1.333\\-1.333&1.116&0.217\end{bmatrix}}{\begin{bmatrix}R\\G\\B\end{bmatrix}}}$

${\displaystyle {\begin{bmatrix}R\\G\\B\end{bmatrix}}={\begin{bmatrix}1&0.000092303716148&-0.525912630661865\\1&-0.129132898890509&0.267899328207599\\1&0.664679059978955&-0.000079202543533\end{bmatrix}}{\begin{bmatrix}Y\\Db\\Dr\end{bmatrix}}}$

你可能會發現YDbDr的Y分量等同於YUV的分量。Db和Dr也類似於U和V如下：

${\displaystyle Db=}$	${\displaystyle +3.059U}$
${\displaystyle Dr=}$	${\displaystyle -2.169V}$

參考書目

• Shi, Yun Q. and Sun, Huifang Image and Video Compression for Multimedia Engineering, CRC Press, 2000 ISBN 0-8493-3491-8