Why isn't there a special setting for B&W movies?

[zambelli]

Let me just start off by saying that I'm not a codec developer, but simply a codec user. What I'm suggesting is based on my amateur assumptions, and not any real research. Just a disclaimer... :)

I think DivX should have a special setting for B&W movies. AFAIK, grayscale images have only 256 shades of gray, which is equivalent to 8 bits of information for every pixel stored. DivX, on the other hand, and please correct me if I'm wrong, is a 16-bit color format. So when we encode B&W movies using DivX, aren't we actually wasting 1 byte for every pixel we encode? Wouldn't it make sense if there were a special B&W option in DivX encoding that would make the codec use only 8-bits per pixel? This would allow us to double the quality of any B&W rip, wouldn't it?

I'd like to hear some experts' opinions on this.

[Q-Ball]

Hmmmm

Technically thats not right..
The black and white video footage still has as many shades of grey as real life, not just 256, but you would still be able to discard the colour information that the codec stores, and use the extra bits for the brightness.

Is that right?

Q :confused:

[rmatei]

You all assume that Divx uses RGB which it doesn't, and YUV handles color totally differently and more efficiently.

More on YUV:
http://www.electric-words.com/dict/y/yuv.html
http://www.inforamp.net/~poynton/notes/colour_and_gamma/ColorFAQ.html
http://everything2.com/index.pl?node=Y(R-Y)(B-Y)&lastnode_id=466997