X11 in 3x12bit or 3x16 bit colors??

05/02/2009 - 19:28 von user | Report spam
Hello,

(sorry, I'm belgian and gone talk in english).

This morning I was wandering why the color depth of images didn't change
since about 1989 (?), when I/ my colleagues used a 24°8 grapĥics card on a
MacIIx. (some scanners do have 48 bit, but no computer/OS?)

If you make a gradient in gray, you might see some borderlines, simply
because there are only ... 256 gray values...(in 3x8 bits) Same problem
for a blue, red or green gradient...
And if you look on your digital television, (is it 3x8bits?), you will see
clouds or snow which look very bad in their white and gray values..


I thought, somebody like sgi.com could have more colordepth...
I found this article:
http://en.wikipedia.org/wiki/Color_depth
(there is a 6x8 bit tv system , based on 6 axes for colour space, which has
3(?) dimensions..)

You can link to these cards:
http://en.wikipedia.org/wiki/ATI_FireGL
Some of these cards seem to work with unix, others with NT.
But: which (linux/bsd) OS has 3x12 or 3x16 bit colors??
It seems the applications do something with it... (pumping directly to the
graphics card?). But there is no Photoshop in 3x16 bit color, I guess??


I have seen Xmacbsd-1-bit and Xmacbsd-8-bit (from netbsd.org) in the year
1995, and I suppose an X system in a reasonable multiple of 2 is possible,
so 3x16bits color??


BTW, I'll be at FOSDEM.org this weekend. If good weather, walkin' in
Brussels ;-)

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Lesen sie die antworten

#1 Thomas Richter
20/03/2009 - 16:05 | Warnen spam
user wrote:
Hello,

(sorry, I'm belgian and gone talk in english).

This morning I was wandering why the color depth of images didn't change
since about 1989 (?), when I/ my colleagues used a 24°8 grapĥics card on a
MacIIx. (some scanners do have 48 bit, but no computer/OS?)

If you make a gradient in gray, you might see some borderlines, simply
because there are only ... 256 gray values...(in 3x8 bits) Same problem
for a blue, red or green gradient...
And if you look on your digital television, (is it 3x8bits?), you will see
clouds or snow which look very bad in their white and gray values..



Different reason - the snow comes from quantization artifacts, from the
quantizer within the video codec, not from the quantization due to the
component precision. Higher bit depth viewing devices do exist, but I'm
not aware of one that would run under X11 (nor an extension of X11 for
it), and only specialists can afford them - high dynamic range images
are used for example in medical imaging, there for inspection of digital
Xrays. The ones I know (from BARCO) have 10 bits resolution.

However, you usually want more precision at the scanning device than at
the displace device - this is because usually you want more than just
rendering the scanned result directly to screen, and processing the
image will cost precision. You're better off here if you have some
overhead of "spare" precision.

But: which (linux/bsd) OS has 3x12 or 3x16 bit colors??



None I'm aware of. Proprietary Windows drivers for HDR displays have it,
but IIRC, X11 doesn't specify anything beyond 8bpp (per component, that is).

It seems the applications do something with it... (pumping directly to the
graphics card?). But there is no Photoshop in 3x16 bit color, I guess??



While I'm not a photoshop expert, I would believe it can process images
in 16bpp - see above - this even makes sense if your monitor displays
only 8bpp.

So long,
Thomas

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