QUOTE(robcat2075 @ Jan 9 2012, 08:31 AM)
"32-bit color" can mean several things...
-24 bits are stored in 32-bit holes because it's faster to move 32 bits than just 24 bits. This is typically what graphics cards mean by 32 bit color.
-24-bits of color + 8 bits of alpha channel. This may be relevant for semi transparent displays like Aero. I rarely hear of apps like Photoshop talk of "32-bit color" even though they have used 24+8 for their files for decades. Photoshop typically refers to itself as 8 bits per color or 16 bits per color (which would be 48 bit color. 64 bits if you added an alpha channel but I've never seen anyone say "64-bit color")
-Some way to hold more than 8 bits per color, like your graphics card's 30 bit color. But then where's the alpha channel? Unfortunately there isn't a standard way to talk about these things.
A:M can render to 24+8 in its targa and PNG formats and with OpenEXR (a floating point format) can render to a nearly unlimited dynamic range
Only some very special displays can show more than 8 bits per color and most flat-panel displays are faking it to display even that.
You're right. I was wrong. 32 bit color must be 24 bit color with alpha.
The ATI catalyst driver for my ATI Firepro equates 24 color as 8 bit color(as it is 3 channels of 8bit). The ATI catalyst driver has a 10 bit option to be used instead of 8 bit. This 10 bit option would be 30 bit color, 3 channels of 10 bit. And logically, I think we'd both have to conclude that a claim of 40 bit color is 3 channels of 10 bit plus alpha. If there is any logic to this 64 bit claim you speak of from Adobe, then I guess that would mean that the latest Photoshop programming is technically capable of handling 16 bit color(3 channels of 16 bit plus alpha), or 48 bit color. Wiki says: "The HDMI 1.3 specification defines bit depths of 30 bits (1.073 billion colors), 36 bits (68.71 billion colors), and 48 bits (281.5 trillion colors).  http://www.hdmi.org/learningcenter/kb.aspx?c=3
HDMI Licensing, LLC.. 2006-11-10" (I suppose this would mean defining proper color counts for 10 bit, 12 bit, and 16 bit color of 3 channels each.) So... that means Adobe Photoshop is technically capable of handling 281.5 trillion colors... sheesh. Which, I suppose this means that Photoshop retains the color information from a 48 bit scan correctly. Then this 64 bit color claim just doesn't sound so glamorous... (The current Sony Sound Forge makes a 64 bit sound claim... does that mean it's really 48 bit sound?)
Your also right on displays. External 30 bit displays are slim pickings. Out of 332 monitors, newegg.com has 12 that are 30 bit. Out of these 12, ten of those claim they meet this new 1.07 standard for 10 bit. And they ain't cheap.
All that said... I'm on the low end of this new standard. Just 10 bits. And enabling that breaks lots of 3rd party programs. And yes, I didn't pay for the internal Dreamcolor display on my laptop(it was expensive, and the card itself still outputs 30bit color through the DisplayPort.), so when I enable 10 bits, the card is calculating the numbers, but the display is faking it. That said, for whatever reason, it still looks a lot better when that option is enabled then when it isn't. Couldn't rely on it for color values though.