RGB, FULL RBG及色差問題

chhanthony

因為我啱啱玩呢樣野冇耐, 所以想知多少少

咁應該用咩判斷色彩係咪正確? ...
Kimjoacky 發表於 2011-10-20 09:59

唔可以話用Ycbcr 4:4:4係錯，不過樓主可以花少少時間睇下以下文章，可能有新嘅啓示

http://www.audioholics.com/tweak ... ck-levels-xvycc-rgb

xvYCC - a Marketing Gimmick? Mostly.

With xvYCC, the range is again extended to 0-255 as is expected, since digital TVs have no under- or over-shoot as did analogue television signals. This will effectively override (in theory) any RGB or YCbCr settings on your source, AV receiver, or display. The idea is that the xvYCC color gamut is only effective when all components in a chain support it. While several AV receivers and displays support xvYCC color space, currently only the PlayStation3 provides xvYCC as a source. Here's where it gets dicey: The Blu-ray specification for movies (BD-ROM) does not support Deep Color or the new xvYCC color space. Oops.

I'll say it again: Blu-ray and HD DVD movie formats are limited to 8-bit 4:2:0 YCbCr. To our knowledge, there is no move to add xvYCC expanded color capability to the BD-ROM specification. In addition, issues of backwards compatibility would be extremely difficult to overcome, rendering any new 10-bit or higher formats unplayable on legacy BD players. The only solution would be to take advantage of larger BD storage media and issue discs with dual data streams for video (double sided or dual layer if you will).

Currently, Hollywood films are telecined directly to digital, with masters stored on D5 tape in 10-bit 4:2:2 format. While this is better than the 8-bit 4:2:0 present on current media, it's still not 12- or 16-bit Deep Color or even utilizing the xvYCC color space. Without mastering and the ability to store xvYCC on source material (other than games which are generated via PC video cards) it seems that xvYCC is largely a marketing gimmick, save the new lines of camcorders, etc which boast 10-bit recording and xvYCC support. Somehow, eliminating the occasional color banding in home movies isn't exactly the incredible leap in technology for which most of us were hoping.

dominickwok

但係4:2:2睇落 "好似" 比4:4:4淡色左
Kimjoacky 發表於 2011-10-19 23:31

I doubt you actually see any difference.  Below is an excellent article to explan what is 4:2:0, 4:2:2, and 4:4:4.

http://www.spearsandmunsil.com/articles/choosingacolorspace.html

If you really notice any difference at all (you may have "golden eyes"), it is either the BD player introducing errors when converting 4:2:0 (from BD disc) to 4:4:4, or the display is introducing errors when processing the 4:4:4 signal (e.g. 4:4:4 -> 4:2:2 -> native video processing -> 4:4:4 -> RGB -> display panel).

chhanthony

I doubt you actually see any difference.  Below is an excellent article to explan what is 4:2:0, 4 ...
dominickwok 發表於 2011-10-20 13:55

dominickwok兄分享嘅文章解釋得好清楚，好值得參考，多謝dominickwok兄先

簡單啲講

揀YcbCr 4:2:2
1 Blu-ray Disc 以4:2:0 儲存
2 由Blu-ray Player轉成4:2:2輸出
3 Display 收到4:2:2轉成4:4:4
4 Display將4:4:4轉成RGB輸出畫面

揀YcbCr 4:4:4
A
1 Blu-ray Disc 以4:2:0 儲存
2 由Blu-ray Player轉成4:4:4輸出
3 Display將4:4:4轉成RGB輸出畫面
或
B
1 Blu-ray Disc 以4:2:0 儲存
2 由Blu-ray Player轉成4:4:4輸出
3 Display 收到非4:2:2訊號將4:4:4轉成4:2:2
4.Display再由4:2:2換成4:4:4
5 Display將4:4:4轉成RGB輸出畫面

揀RGB (16-235)
A
1 Blu-ray Disc 以4:2:0 儲存
2 由Blu-ray Player轉成4:4:4
3.Blu-ray Player將4:4:4換成RGB輸出
4 Display收到RGB後乜都唔做輸出RGB畫面
或
B
1 Blu-ray Disc 以4:2:0 儲存
2 由Blu-ray Player轉成4:4:4
3.Blu-ray Player將4:4:4換成RGB輸出
4 Display收到非4:2:2/4:4:4輸號將RGB轉做4:2:2/4:4:4訊號
5. Display再將4:2:2/4:4:4訊號成RGB輸出畫面

到底用Blu-ray Player做convertion定係用display就要睇下邊部機做convertion好啲
問題係就算知道Blu-ray Player嘅convertion好啲，用Blu-ray Player做整YCbCr轉換RGB係好啲
但用家唔知道display收到RGB訊號時會唔會再用RGB做多次convertion。

用家可以用一啲測試圖去試下唔同嘅設定，但一般用YCbCr會穩陣過RGB
而4:2:2又會穩陣過4:4:4

AUTO係最最穩陣..