1 - Multimedia Data Representation

pixel

combination of 3 colored lights - small points of colored light arranged in a grid

black

the absence of light

white

full intensity of each color

computing on representations

when digital informaiton is changed through computation

examples: red eye removal, photo corrections, color changes, artistic effects

levels graph

graph that represents values of pixels

brightness

how close to white the pixels are

contrast

the size of difference between the darkest and lightest portions of the image

Nyquist rule

a sampling rate must be at least twice as fast as the highest frequency

bit depth

number of bits used to represent each sample

image

long sequence of RGB pixels

audio compression

removing sounds that are too high/too low to hear

luminance

humans are quite sensitive to small changes in brightness

chrominance

people are not sensitive to small differences in color

lossy

MP3 uses a variety of methods to create a small data files (human ears cannot detect log frequency sounds stereographically so MP3 may record low frequency sound in mono and play the same sound to both speakers)

lossless

recreation of the compressed file recreates the original without loss of any data (.zip file format)

fax machine

simple computer that scans a black and white page into about 1000 × 2000 pixels, which are sent using a modem to another fax machine, which prints the pixels out on a page

latency

time it takes for information to be created or delivered

bandwidth

amount of data that can be transmitted per unit of time