what is Alpha channel?

[Taipei Man]

Hi,

Just checked the Matrox site about the reason of some color depth not
displayable in video.
The reasons are all about a "Alpha Channel" issue. What exactly is that?
Based on that description, it seems a four digit scheme will work use Video
while 3 digits' will not.
For example,
16 bit 4-4-4-4 work
24 bit 8-8-8 not work

How about 32 bit(8-8-8-8-)?

Harry

[Alastair Upton]

The alpha channel (transparency component) typically contains as many bits
as a color channel. Therefore, a pixel is defined as R-G-B-A

For example, an 8-bit alpha channel can represent 256 levels of
transparency, from 0 (the pixel is transparent) to 255 (the pixel is
opaque). For a 16-bit pixel the 4-bit alpha channel defines transparency
values of 0 to 15.
In the case of a 24-bit pixel, no alpha channel is included therefore it
won't work. it should, however work with 32-bit as the alpha channel is
included.

Alastair

[harry]

Then my next question is why Marvel G200TV does not support 32bit color
depth in my NT4 system?
I have to lower it to 16bit every time in order to see picture.

Alastair Upton <AUp...@netik.com> wrote in message
news:939298182.23440.0...@news.demon.co.uk...