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RGB

eliu
1 RGB
Promote 3 Bookmark 02009-10-03quote  

目前的RGB 還是 24-bit,R/G/B 只有one byte,所以只能顯示 256 種灰階,只要長寬大於 > 256 的圖,灰階變化就不夠。

其實有些高階的繪圖工作站 RGB 是 48-bit的,R/G/B channel 是 16-bit,這樣就可以顯示 65536種灰階。

我們可以看到 GTK & X11 介面的 RGB 早就是 48-bit 的,只可惜不知道什麼時候我們的 RGB 才會進化成48-bit的。

GTK & X11
typedef struct {
  guint32 pixel;
  guint16 red;
  guint16 green;
  guint16 blue;
} GdkColor;

typedef struct {
        unsigned long pixel;/∗ pixel value */
        unsigned short red, green, blue;/∗ rgb values */
        char flags;         /∗ DoRed, DoGreen, DoBlue */
        char pad;
} XColor;

 

Windows 好像沒聽過有 48-bit 的RGB,只要 Windows 不動,我們就永遠停留在 24-bit RGB?

Windows Win32
COLORREF RGB( BYTE byRed, BYTE byGreen, BYTE byBlue );

當然我們需要48-bit 的顯示卡 & 顯示器monitor & 印表機printer 。另外,不知道有什麼 image file 支援 48-bit RGB,TIFF 好像有。還有,我們需要 48-bit RGB 的 digital camera,這已經有了

edited: 11
coolcd
2
Promote 0 Bookmark 02009-10-03quote  

之前看過一些 photoshop 教學,會把相片轉成 16bit RGB,再去處理,得到的色彩看起來很鮮豔,可是我覺得看起來有點假,猜想可能是螢幕沒有支援 16bit 的關係。

eliu
3
Promote 0 Bookmark 02009-10-03quote  

coolcd
之前看過一些 photoshop 教學,會把相片轉成 16bit RGB

不知道為何要這樣做。目前的 dc or dslr應該都是 24-bit 的

edited: 1
coolcd
4
Promote 0 Bookmark 02009-10-03quote  
eliu

不知道為何要這樣做。目前的 dc or dslr應該都是 24-bit 的

記得是為了避免調整階調時斷階的問題

ziyawu
5 RGB
Promote 0 Bookmark 02009-10-03quote  
eliu

當然我們需要48-bit 的顯示卡 & 顯示器monitor & 印表機printer 。另外,不知道有什麼 image file 支援 48-bit RGB,TIFF 好像有。

CinePaint 支援的有 DPX、OpenEXR 和 16-bit TIFF。
(據說電影畫面編輯的最低要求是 16 位元深度)

Photoshop 的 PSD 也可以。

coolcd
6
Promote 0 Bookmark 02009-10-03quote  

google 了一下 CinePaint

原來這看似不起眼的程式這麼厲害,等我切到 Debian 也來用用看

Top Reasons to Use CinePaint

  1. Support for 8-bit, 16-bit and 32-bit color channels of deep paint.
  2. High fidelity image file types such as DPX, OpenEXR and 16-bit TIFF. These files can't be opened in ordinary 8-bit image applications (e.g., GIMP) without crushing them.
  3. High Dynamic Range. HDR images can go brighter than white. Ordinary images can't be brighter than a white sheet of paper (0=black, 1.0=white).
  4. Gallery-quality printing. B&W photographs have only one color channel and degrade quickly when manipulated as 8-bit images. CinePaint has higher fidelity and offers a 16-bit printing path to the print-head using GutenPrint.
  5. Color Management System. CinePaint uses LittleCMS.
  6. Flipbook. Movie playback of short sequences of images in RAM.
  7. Innovation. CinePaint offers features that go beyond ordinary painting tools.
  8. It's used to make feature films at major studios.
  9. Open Source. With various OSS licenses, because it uses code from various sources, including GPL, LGPL, BSD, and MPL.
  10. Free.
  11. Friendly professional developers. Polite discussion forums.
  12. Being a CinePaint developer can be a good career move. CinePaint developers have gotten jobs at companies such as DreamWorks Animation, Sony Pictures Imageworks, and Apple.

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