24vs32 bit...
Friday, July 25, 2003 by EventHorizon | Discussion: WinCustomize Talk
Ive noticed that with generic vid cards, (Like the one I use 
) the highest color setting avaliable is 24 bit. (A tad more than 16 million colors) While on other name brand cards, (Nvidia, ATI) will go up to 32 bit... (More than a billion colors if Im not mistaken) Can you tell the difference between 24 and 32 bit? (Like between 16 and 24...Color-banding shows up a lot with 16, but not with 24) And is 32 necessarily better than 24?
) the highest color setting avaliable is 24 bit. (A tad more than 16 million colors) While on other name brand cards, (Nvidia, ATI) will go up to 32 bit... (More than a billion colors if Im not mistaken) Can you tell the difference between 24 and 32 bit? (Like between 16 and 24...Color-banding shows up a lot with 16, but not with 24) And is 32 necessarily better than 24?
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Tech-Cat
Reply #3 Friday, July 25, 2003 3:40 PM
Reply #3 Friday, July 25, 2003 3:40 PM
The human eye cannot tell a difference between 24-bit color and 32-bit color. I do see a difference between 24-bit display and 32-bit display. There must be other factors involved in the two different displays because one does not seem more colorful than the other. One just seems to have more detail or can display details more clearly than the other.
Koasati
Reply #4 Friday, July 25, 2003 3:43 PM
[Message Edited]
Reply #4 Friday, July 25, 2003 3:43 PM
| Colour Setting | Colours on Screen at Once | Description |
 |
| 16 Colour | 16 Colours | Display's pictures in almost two tones that look very rough and pixely |
| 256 Colour | 256 Colours | Displayed pictures that look grainy and photos look like cartoons |
| 16bit High Colour | 65,536 Colours | Most people use this setting. Pictures look real and only slight banding appears in smooth shaded areas such as sky photos. |
| 24bit True Colour | 331,776 Colours | Gives a much better image than 16bit, and shows pictures without any artefacts. Some computers only display 24bit and not 32bit colour. |
| 32bit True Colour | 1.6 Million Colours | The best image quality for displaying images on computers. Some computers only display 32bit and not 24bit colour. |
[Message Edited]
Frogboy
Reply #5 Friday, July 25, 2003 3:56 PM
Reply #5 Friday, July 25, 2003 3:56 PM
24bit does 16.8 million colors.
32bit does billions of colors.
32bit does billions of colors.
White_Moth
Reply #6 Friday, July 25, 2003 4:16 PM
Reply #6 Friday, July 25, 2003 4:16 PM
I just want to see color number 407,281,834,101
[Message Edited]
[Message Edited]
Koasati
Reply #7 Friday, July 25, 2003 4:19 PM
Reply #7 Friday, July 25, 2003 4:19 PM
I figure you know what you're saying Brad, and now, I can't find the page where I got that info.................... but I can find conflicting information concerning 32 bit color. 
Hus
Reply #8 Friday, July 25, 2003 4:35 PM
Reply #8 Friday, July 25, 2003 4:35 PM
The simplest way to test it visually, is create a multi-colored gradient going from one end of the screen to the other, and look at the picture in different color depths. You will notice a difference between 16, 24 and 32-bit color depths. 
Frogboy
Reply #9 Friday, July 25, 2003 5:06 PM
Reply #9 Friday, July 25, 2003 5:06 PM
Bits has to do with how much color can be dsiplayed at once. It's 2^N. Where N is the # of bits.
N^15 is 32k colors. N^16 is 65,535. N^24 is 16.8.
256 color is also referred to as 8 bit color (N^8).
EventHorizon
Reply #10 Friday, July 25, 2003 6:12 PM
Reply #10 Friday, July 25, 2003 6:12 PM
Yea, thats another funny thing. 15bit color...The only place Ive seen it was our old P166 MMX runnin' Mandrake Linux 8.2. I said it could display both 16 and 15 bit color... Whats up with that? Is it an alternative to 16bit incase 16bit is too hard on the vid-card? Or is it some standard in some other country?
DavidK
Reply #12 Friday, July 25, 2003 6:46 PM
Reply #12 Friday, July 25, 2003 6:46 PM
24bit color and 32bit color look exactly the same. There is more data in 32bit color which has to do with image format. 8bits of extra binary code in the header for computers to manipulate, like exposure data, transparency etc.
paxx
Reply #13 Friday, July 25, 2003 7:18 PM
Reply #13 Friday, July 25, 2003 7:18 PM
I was told before that the 32 bits was 24 bits + 8 bits alpha channels. But I found that 8 bits transparency (such as XP icons) also work in 24 bits mode, so I'm not sure anymore.
DavidK
Reply #14 Friday, July 25, 2003 7:57 PM
Reply #14 Friday, July 25, 2003 7:57 PM
The way I understood it is like what paxx says, there is no 32bit 'color' in RGB. 24bit and 32bit color both have 16.8 million colors. 32bit RGB has an extra 8bits for alpha levels and other header data. I've also heard that CMYK uses the extra 8bits for color, so all 4 channels have 8bits. I'm not sure if any of this is true though...
I hear they're developing 48bit and 64bit color systems. That will be interesting.
Jafo
Reply #15 Friday, July 25, 2003 9:36 PM
Reply #15 Friday, July 25, 2003 9:36 PM
The problem arises when 'physics' declares an infinite colour range exists, as does an infinite audio frequency variation, or volume increments....but human physiology will only determine definable gradations of any of these.....eg, the eye cannot distinguish 16.7 million colour variations, nor can your brain/perception benefit from their use.....the benefit from going from 8 bit to 16 bit is about as useful as it gets. A computer can tell 'magic pink' is 255,000,255....but the human eye will never see that 255,000,254 is any different...except the proggy it's used in will spit a dummy and show it as 'pink' instead of 'invisible/transparent'...
EventHorizon
Reply #16 Friday, July 25, 2003 11:05 PM
Reply #16 Friday, July 25, 2003 11:05 PM
Another thing...(With the mention of 48bit color) Why do many scanners boast 48bits of color perception? (Also, the cheaper models have 'only' 42bits of color perception)Who needs that many colors? As stated earlier, the eye cannot define between magic pink and its nearest neighbor, so, whats the point of 42 or 48bits of color? Is it just hype? Or is there some real use for billions upon billions of colors*?
*Color not colour. (Brits and Aussies are excused from this correction as their dialect has not yet matured to the point of removing the unnecessary vowel) Just kidding, Jafo. 
*Color not colour. (Brits and Aussies are excused from this correction as their dialect has not yet matured to the point of removing the unnecessary vowel)
Just kidding, Jafo. 
Jafo
Reply #17 Saturday, July 26, 2003 12:18 AM
Reply #17 Saturday, July 26, 2003 12:18 AM
Oh...why not call it 'kuller' or 'kullah' and be done with it....philistines....
MadIce
Reply #18 Saturday, July 26, 2003 2:00 AM
Reply #18 Saturday, July 26, 2003 2:00 AM
Paxx is right. In 32-bit colors only 24-bits are used. 8 bits per channel for Red, Green and Blue. The 8 remaining bits are not used.
32-bits can have a significant advantage in speed. 32-bits are handled much faster than 24-bits when handling pixels individually, because 32-bit pixels can be accessed in one "aligned" read or write operation. On the other hand 24-bit pixels can only be accessed 8-bits at a time or need to be accessed by one or two 32-bit aligned accesses with a lot of bit shifting.
Games engine coders are very aware of these issues and when true colors are used they rather use 32-bit modes than the slower 24-bit modes. The same goes for DesktopX. Internally DX works with 32-bit bitmaps for the same reason. Games and DesktopX are using the fourth channel for per pixel alpha blending (translucency) information.
In graphics drivers it may make a difference too, but some hardware has specialized 24-bit manipulation hardware. Chances are that 32-bit is still faster, because not all graphics opertions are done by graphics hardware.
The Matrox Parhelia is a special case. That graphics card is using 10-bits (!) per channel to increase the quality of the color. So, they can use 1024 values per channel. That allows the Parhelia to use 1,073,741,824 instead of 16,777,216 colors.
Why does it make a difference to have that many colors? Assume you have a picture of a white teapot. In 256 color modes you will not see nice gradients in the picture but bands of colors instead. Looks rather ugly. In true color that effect will be less obvious and the image looks much smoother. The Parhelia clearly wins when showing a lot of different grades of the same color. It looks more natural.
On a monitor 8 or 10-bits per channel is enough, but for (professional) high quality printing there are a lot more colors. 48-bit (16-bit per channel) scanners are able to scan and to save these high quality images without losing much color information. Note that high quality printing also uses 2400 and often more than 4800 DPI in which the number of colors is much more important than on a monitor.
The same is true for ultra high resolutions used by movies. On such systems 8 or 10 bits per channel would cause these ugly bands to appear again. Such systems use 16-bit per channel or more.
Graphics programs are able to use 24-bit color formats. Also, some software is able to use 32-bit formats (which is good news for games programmers). These days 48, 64, 96 and 128-bit formats start to appear in professional software.
In todays graphics cards we also see high precision color being used for real time 3D rendering. Nvidia not only supports 8-bits per channel pixel and vertex shaders, but also 16-bits per channel and even a 32-bit floating point modes. And yes, other brands have similar capabilities, although ATI's R300 is using a maximum of 24-bits per channel (96-bits per pixel) which is expanded to 128-bits per pixel when written to the frame buffer.
32-bits can have a significant advantage in speed. 32-bits are handled much faster than 24-bits when handling pixels individually, because 32-bit pixels can be accessed in one "aligned" read or write operation. On the other hand 24-bit pixels can only be accessed 8-bits at a time or need to be accessed by one or two 32-bit aligned accesses with a lot of bit shifting.
Games engine coders are very aware of these issues and when true colors are used they rather use 32-bit modes than the slower 24-bit modes. The same goes for DesktopX. Internally DX works with 32-bit bitmaps for the same reason. Games and DesktopX are using the fourth channel for per pixel alpha blending (translucency) information.
In graphics drivers it may make a difference too, but some hardware has specialized 24-bit manipulation hardware. Chances are that 32-bit is still faster, because not all graphics opertions are done by graphics hardware.
The Matrox Parhelia is a special case. That graphics card is using 10-bits (!) per channel to increase the quality of the color. So, they can use 1024 values per channel. That allows the Parhelia to use 1,073,741,824 instead of 16,777,216 colors.
Why does it make a difference to have that many colors? Assume you have a picture of a white teapot. In 256 color modes you will not see nice gradients in the picture but bands of colors instead. Looks rather ugly. In true color that effect will be less obvious and the image looks much smoother. The Parhelia clearly wins when showing a lot of different grades of the same color. It looks more natural.
On a monitor 8 or 10-bits per channel is enough, but for (professional) high quality printing there are a lot more colors. 48-bit (16-bit per channel) scanners are able to scan and to save these high quality images without losing much color information. Note that high quality printing also uses 2400 and often more than 4800 DPI in which the number of colors is much more important than on a monitor.
The same is true for ultra high resolutions used by movies. On such systems 8 or 10 bits per channel would cause these ugly bands to appear again. Such systems use 16-bit per channel or more.
Graphics programs are able to use 24-bit color formats. Also, some software is able to use 32-bit formats (which is good news for games programmers). These days 48, 64, 96 and 128-bit formats start to appear in professional software.
In todays graphics cards we also see high precision color being used for real time 3D rendering. Nvidia not only supports 8-bits per channel pixel and vertex shaders, but also 16-bits per channel and even a 32-bit floating point modes. And yes, other brands have similar capabilities, although ATI's R300 is using a maximum of 24-bits per channel (96-bits per pixel) which is expanded to 128-bits per pixel when written to the frame buffer.
MadIce
Reply #19 Saturday, July 26, 2003 2:25 AM
Reply #19 Saturday, July 26, 2003 2:25 AM
Koasati and Frogboy are a bit off. For the PC and simple graphics we have the following formats:
1-bit (2 colors)
4-bits (16 colors)
8-bits (256 colors chosen from a palette of 16,777,216 colors)
15-bits (32,768 colors)
16-bits (65,536 colors)
24-bits (16,777,216 colors)
32-bits (16,777,216, because 8-bits are not use for color information)
The extra 8-bits (the Alpha channel) can be used for per pixel alpha blending (translucency).
In DirectX we have a lot more variations, like a 16-bit format with 4-bits color channels and a 4-bits Alpha channel or a 16-bit format with 5-bit color channels and a 1-bit Alpha channel. In DirectX the Alpha channel is sometimes used to store Z-buffer information.
[Message Edited]
1-bit (2 colors)
4-bits (16 colors)
8-bits (256 colors chosen from a palette of 16,777,216 colors)
15-bits (32,768 colors)
16-bits (65,536 colors)
24-bits (16,777,216 colors)
32-bits (16,777,216, because 8-bits are not use for color information)
The extra 8-bits (the Alpha channel) can be used for per pixel alpha blending (translucency).
In DirectX we have a lot more variations, like a 16-bit format with 4-bits color channels and a 4-bits Alpha channel or a 16-bit format with 5-bit color channels and a 1-bit Alpha channel. In DirectX the Alpha channel is sometimes used to store Z-buffer information.
[Message Edited]
Koasati
Reply #20 Saturday, July 26, 2003 4:31 AM
Reply #20 Saturday, July 26, 2003 4:31 AM
After doing a google search, on the subject, and reading this thread, I have no idea what is what. There seems to be many conflicting opinions on the subject. I do know that 16 bit is not about as useful as it gets. You only have to view the simple wallpaper on my desktop in 16 bit, to mode to see that. You get the banding Madice talks about.
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Reply #1 Friday, July 25, 2003 2:56 PM