I need help boys.

iwanttosave_2

Please help explain the following to me because my course text is "odd" to say the least and doesn't speak much English.

The question I have to answer is-

What does the term "quantisation" mean in the context of representing images and sound on a computer?


(I only need a few sentences so you don't need to go to in-depth.)

Spanks

elljay20

don't know wanty but how do i get rid of spyware?:D

isofa

It means to fix notes to a tempo with accurate rhythm in music. So if you are playing slightly incorrectly / out of time into a sequencer, a quantization function will bring the notes strictly into time, so it's "perfect", but it can sound a bit wooden too.

Never come across it in images.

iwanttosave_2

elljay20 wrote: »

don't know wanty but how do i get rid of spyware?:D

Poke it in the eye



(or run your scanners which you should have on the computer, if not google ad-aware and download that and run it)

iwanttosave_2

isofa wrote: »

It means to fix notes to a tempo with accurate rhythm in music. So if you are playing slightly incorrectly / out of time into a sequencer, a quantization function will bring the notes strictly into time, so it's "perfect", but it can sound a bit wooden too.

Never come across it in images.

The only thing I have found in my course text about it says...

"The mapping of samples (or pixels) to numbers is know as quantisation."


Helpful isn't it. :rotfl:

krysus

In terms of sound....

Any sound is made up of a continous wave.... but to store it digitally that continuous wave needs to be chopped up into tiny slices, and then the amplitude (volume) of each slice determined to a particular degree. The whole process is called 'sampling'.

Basically, from an audio CD perspective, each second of sound is split into about 44,000 slices (technically, 44kHz). Higher sampling rates = more detail = better quality.

Sound: http://en.wikipedia.org/wiki/Quantization_%28sound_processing%29
Images: http://en.wikipedia.org/wiki/Quantization_%28image_processing%29

A graph showing quantization:
http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Pcm.svg/250px-Pcm.svg.png

isofa

Ahhh that's very different to quantization from a musicians perspective, you'll need to check what they actually want!

iwanttosave_2

:think: :undecided

*moves on to the next question*

Ugh binary code.

Actually thinking about it, the slices Kysus talks about could always be the mapping they talk about. Will have a nose at those links.

krysus

The OP did say "in terms of representing sound and images on a computer" so i took it to mean making a digital representation of an analogue source...

Like you say, two very different things...

Keldin

Quantization is a process whereby you constrain something or restrict the number of possible values. Such as from a continuous set (real numbers) to a discrete set (integers).
In image and sound you would be reducing the number of discrete symbols in a stream or approximating a set of values. This allows compression of the data stream.
See PCM in audio where an analogue signal is quantised? by regular sampling at specific intervals to produce a digital signal (telephony uses 8-bit quantisation compared to compact discs 16 bit) or JPEG in images.

K

sicker

Iwanttosave, Only 10 people understand binary numbers.