View Full Version : Colours 48 bits 16 bits 8 Bits Channel.

22-06-2006, 09:11 AM
Can someone explain these figures to me? Im talking about 8 Bits/channel in terms of imagery and pictures. I dont really get these. Is it the smaller the number, the better the picture?

And, I heard that there are also different colour channels? Like Red and Blue channels, are these just the channels in which the computer can read and identify?

And what about 48 bit colour? Is that in the same category as 8 Bits/channel? Or is it something totally different.

I need to know more about colours.


Graham L
22-06-2006, 02:20 PM
Any colour can be produced by mixing appropriate proportions of each of the three "primary" colours Red, Green, and Blue. These are additive, which is how the three phosphors in a colour monitor screen are used. If you turn red on fully and the others off, you get a bright red. If you turn them all off, you get "black". (Your inkjet colour printer uses subtractive mixing of the complement colours Cyan, Yellow, and Magenta.)

Each the hardware which produces each primary colour might be referred to as a "channel".
In a digital system, the more bits you use the "smoother" the changes between values. But the more bits used, the more memory is required to save a picture.

The resolution settings for your Windows Desktop start at 256 colours. That actually uses a lookup table in the video system to generate some 8 bit/channel figures for the colour generation hardware. That will use 1 byte/pixel, so it's quite compact.
"65 thousand" would be 16 bits, (two bytes) so is probably a lookup table again.

"16 million" colours are what you can get from 24 bits, that is, 8 bits/channel,
which requires 3 bytes per pixel.

48 bit would probably be 12 bits/channel ... you can fiddle them around like that.gg (google.co.nz)

The first IBM PC colour cards (the CGA) had a maximum colour range of 16 colours.

Colour can get complicated. Probably a search with "RGB" (or "CYMK" the "K" is black, not a colour, but used because a subtractive mix of the primary complements gives a fairly unblack black), will find lots of information. "CGA" will locate a wikipedia article on the Colour Graphics Adapter which will give liks to others.

Graham L
22-06-2006, 02:38 PM
Of course ... 48 bits would be 16 bits/channel so 6 bytes per pixel. That would give a lot of possible colours, certainly more than anyone could tell apart.

23-06-2006, 09:16 AM
There are 256 colours? Lets see, Red, Blue, green... there are that many? I know, I know, all the shades and stuff, but 16 millions shades? Thats a lot. Just saying. ^^ Thanks anyway.