Hi,
> Oh, and one more thing, that I have been meaning to ask for ages, and I fear
> that I may be opening a can of worms here <vbg> but can someone explain to
> me about "bits" ie what is the difference between 8 bit and 16 bit files?
The larger the number of bits, the more colours you can have in the
file.
Suppose you have 8 cans in a row, and each can is either empty or contains
exactly one worm. You can think of each can as a bit (BInary digiT).
The pattern of empty and worm-filled cans can represent a number. If
we take O to mean an empty can, and ~ to stand for a can with a worm
in, we might see a pattern like this:
OO~~OO~O
Each position has a possible value, depending on whether or not there's
a worm in the can at that position. If there's no worm in the can,
then the value is always 0 (zero), whatever the position.
Start at the rightmost end, which has value 1 for a worm. The next left
has the value 2 for a worm, the next is 4, then 8 - constantly doubling.
As you go left you keep adding the value for the worm-filled cans to the
total.
So the value of the example above is 50 in decimal notation:
0 + 0 + 32 + 16 + 0 + 0 + 2 + 0.
8 bits means you have 8 cans and up to 8 worms, which gives a
maximum value of 255 ((2 to the power of 8)-1).
16 bits means you have 16 cans and up to 16 worms, which gives a
maximum value of 65535 ((2**16)-1).
For each pixel there are 8 or 16 (or whatever) distinct cans of worms.
The value that those cans represent, determines the colour of the
pixel. It does this by acting as an index into a table of 3 hardware
registers; each register determines the intensity of one of the
primary colours, red, green and blue.
The table will contain n rows where n is the maximum value for the
number of bits (cans of worms) for each pixel.
--
Cheers,
Bob
