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Per Pixel Color Component Output / Bit Display Pipeline....

Last response: in Graphics & Displays
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April 23, 2006 2:20:40 AM

For the GeForce 7900GT... Does anyone know what the "Per Pixel Color Component Output" is and if there is a "Bit Display Pipeline" what the values are.....
April 23, 2006 5:32:43 AM

"Per Pixel Color Component Output" refers to the depth of each color. 24bit Turecolor has 8bit Red, 8bit, Blue, and 8bit Green. 32bit color is basically the same as it offers 8bit for all three but has an 8bit segment for the alpha value. Beyond that there is 10bit and 16bit per color channel but you will only see that on professional cards like FireGL and Quadro. There are differeing formats for using the 32 bits. 8:8:8:8, 10:10:10:2, etc.

A 7900GT will use 32bit color.
April 23, 2006 10:31:43 PM

For discussion:

Let's set the 16.7 million color set as a start.

At 10bit and 16bit are there more available colors?

And is there a need for a monitor with the ability to display the additional information being sent from the video card....

Is it true that the 7900GT type cards also differ from the pro cards in that the pro cards are more aware of pixel accuracy and color depth?

And is this limited to just video/FPS or in a DCC/Photoshop mode are the 7900GT type cards also not very accurate?
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April 24, 2006 6:02:23 AM

"Let's set the 16.7 million color set as a start.

At 10bit and 16bit are there more available colors?”


Yes, there are more colors.

8-bit = 2^8 = 256 color values per channel (RGBA = Red, Green, Blue, Alpha)
10-bit = 2^10 = 1024 colors
12-bit = 2^12 = 4096 colors
16-bit = 2^16 = 65536 colors

*Note: 16-bit color is also called 48-bit mode as there are 16 bits per channel

This translates into:

8-bit = 256^3 (maximum combinations of each color channel value) = 16,777,216 total colors
10-bit = 1024^3 = 1,073,741,824 total colors
12-bit = 4096^3 = 68,719,476,736 total colors
16-bit = 65536^3 = 281,474,976,710,656 total colors

Okay, this is how it works. It is all about precision. The term is less foreboding than it needs to be. Basically, 10bit color has color values between 0 and 1024 verses 8bit with 0 to 255. There are in fact 4 times as many colors in 10bit than 8bit. Here is a nice paper on colors. http://www.w3.org/Graphics/Color/sRGB

HDR is one of those things that also ask a lot of the color scale. The real world has more color values than can be represented in current digital layouts. This is where you will see precision come into play. The more places you can round to, the closer the number is to an exact figure. 0.01234 is more accurate than 0.0123 and so on. Here is something from Nvidia explaining how they increase the color spectrum using additional data.

“High Dynamic-Range (HDR) Imaging
To preserve the wide range of color values in an HDR image, color components must be manipulated using a logarithmic storage format. HDR rendering utilizes 16-bit and 32-bit floating point per color component to represent high-contrast images. This permits all original color data to be available for manipulation in the image processing pipeline. Traditional 8-bit and 16-bit integer color spaces—as well as sRGB, an 8-bit gamma colorspace—constrict color values to the range of 0 to 1. Color values in nature don’t conform to this range. While sRGB, and e-sRGB (a 12-bit gamma color space) do provide a logarithmic representation of the image data, neither color space has the range and precision required to maintain color accuracy during image processing operations. Extending the range and utilizing floating point values to logarithmically express color components permits super whites (values greater than 1.0) and super blacks (values less than 0.0), as well as an almost infinite number of color gradients in between. As a result, HDR imaging allows extremely bright objects and rich dark objects to appear dark in the same image with increased visible detail…”
From http://www.nvidia.com/attach/553409?type=support&primit...

For even more information on HDR encodings for computers you should read a paper by Greg Ward. http://www.anyhere.com/gward/hdrenc/Encodings.pdf


“And is there a need for a monitor with the ability to display the additional information being sent from the video card....”

Not all monitors are created equal. CRTs are by far the most dynamic when looking at how each pixel is able to be represented. LCDs are less than CRTs in that they are limited by backlighting etc. Brightside has a really nice LCD that can do “real” HDR rendering.

http://www.brightsidetech.com/

If you look at the monitor reviews we do here at Tom’s (http://www.tomshardware.com/2006/04/21/asus_pw191_lcd/p...) you will see that we test the gamut or the range of colors represented by the display.



“Is it true that the 7900GT type cards also differ from the pro cards in that the pro cards are more aware of pixel accuracy and color depth?”

Generally the pro cards have deeper colors than consumer cards. As I have it stated above, that is changing as HDR is making its way into the consumer space. The traditional sRGB is losing out to the demand for more realistic content in games, video, and general life on the web.
April 24, 2006 6:08:05 PM

Thank you…. I guess I can expect a bill for the excellent journey into the realm of computer generated color.

We are all Einstein’s to some extent, in that we can solve some of the most complex problems except when it comes to pulling the trigger on building a new platform - I was too involved with specifications and went brain dead…(senior moment)… Thanks for the wake up call.

Building is not an issue since I have been involved with electronics since the mid 60’s, started with vacuum tubes, I will say no more. We have come a long way and the ride into the future is truly remarkable and enjoyable. I have been a member of SIGGRAPH since the 80’s and have watched primarily the software developments.

As a fine artist, I recently turned digital and as the programs have matured my present configuration (circa 2000) is bleeding my time away and struggles to keep up. My desire is to build a platform that takes full advantage of the software’s capabilities and will allow for those inevitable hardware upgrades.

Reading the information you supplied has produced a few lively discussions with the engineers at work and we agreed to disagree, leaving me to realize that the technology may be beyond my present needs as a designer working in a 2D environment. Since I plan to move into a limited 3D environment I feel that the 7900GT will do just fine….

Building upon the ASUS P5WD2E-P, staying within my present budget, I know I will continue to create really great artwork and even fly a simulator now and then….

Thank you again and I look forward to another pleasant exchange here on the forumz…
!