Java DTV Graphics APIs are provided by the Personal
Basis Profile in the java.awt package. The
GraphicsEnvironment provides an enumeration of the
GraphicsDevices available. From each device, the
GraphicsConfiguration provides information about the
bounds of the display surface, the color model and image
capabilities. The predefined color models are IndexColorModel
and DirectColorModel.
The java.awt.Color model defines the value ranges for
alpha, red, green, and blue values ranging from 0.0 – 1.0 or 0 –
255. The default color space is sRGB, see
http://www.w3.org/Graphics/Color/sRGB.html.
Devices map those values into the available depths of the devices for presentation.
The IndexColorModel MUST be supported with a
predefined Color Lookup Table containing the following entries that
allow selected ranges for colors in opaque, partially transparent,
fully transparent and opaque grayscales.
|
Transparency |
Red Values |
Green Values |
Blue Values |
|---|---|---|---|
|
Opaque; alpha = 255 |
0, 63, 127, 191, 255 |
0, 31, 63, 95, 127, 159, 191, 223, 255 |
0, 127, 255 |
|
30; alpha = 179 |
0, 85, 170, 255 |
0, 51, 102, 153, 204, 255 |
0, 255 |
|
Transparent; alpha = 0 |
n/a |
n/a |
n/a |
|
Opaque; alpha = 255 |
42, 85, 170, 212 |
Identical to Red |
Identical to Red |
The DirectColorModel MUST be supported with at least
4 bits per pixel for Alpha, Red, Green and Blue.
The Alpha values MUST support 16 levels of transparency from fully transparent to fully opaque.
The Red, Green, and Blue values MUST support 16 levels from none to fully saturated.