|
Y'CbCr (601) from R'G'B'; O. a6 o( L* x1 w# i; C, D
========================================================
) g/ a- a4 I2 S- q% d. _1 PY' = 16 + ( 65.481 * R' + 128.553 * G' + 24.966 * B')( m* v7 R0 k& _
Cb = 128 + (-37.797 * R' - 74.203 * G' + 112.0 * B')
+ c0 S9 I a% s8 i* `Cr = 128 + (112.0 * R' - 93.786 * G' - 18.214 * B')
+ i: f! I+ T6 R+ Y+ d9 T9 E........................................................: Z1 D& s- c3 B+ I9 o8 a
R', G', B' in [0; 1]& Y1 t: n" Q) W+ e7 [0 a/ F ^
Y' in {16, 17, ..., 235}5 z, Z# q- y/ q3 n1 e, C. {& e2 H
with footroom in {1, 2, ..., 15}% S h/ o& ^ H8 z* N" }* r) a
headroom in {236, 237, ..., 254}# X( W/ }+ j. H7 _9 ~; F3 z6 r
sync. in {0, 255}
/ P) ~2 m9 b$ G# rCb, Cr in {16, 17, ..., 240}+ c$ L( A" {7 a! n
您說的128應該是指Cb Cr 的grayscale, 當RGB每channel輸入皆為0時Cb Cr 輸出128, Y 輸出16, 此時應該對應到RGB domain gray level的0, 這就是ADC的DC offset.
/ i1 F$ W5 I" p& K, f: U( K0 r此時, 若Cb 或 Cb 輸出值為131表示輸出的Cb 或 Cr 相位有旋轉, 色度值非正確值
; |/ W& k/ F; z" \您可以參考以下的網頁' z4 N `# t3 h' G- L
http://en.wikipedia.org/wiki/Color_matrix5 Y; O1 Z" w1 v" J0 R( g8 l
或是去找一些color matirx的書籍 |
|