chapter1

bit-map depth

system that uses pixels to make up an image

pixel

smallest picture element that makes up an image

colour depth

number of bits used to represent the colours in a pixel and 8 bit colour depth is 2^8

bit depth

number of bits used to represent the smallest unit in sound or image file the larger the bit depth the better the quality of the sound or the image

image resolution

number of pixels that make up an image

screen resolution

number of horizontal and vertical pixels that make up a screen display

what happens if the screen resolution is smaller than the image resolution

doesn’t represent the full image or downscales the quality

resolution

number of pixels per row and column on a monitor

pixel density

the number of pixels per centimetre squared

vector graphics

images that use 2D points to describe lines and curves and their properties that are grouped together to form geometric shapes

sampling resolution

number of bits used to represent sound amplitude(bit depth)

sampling rate

frequency of sound samples per second

frame rate

frequency of video frames that make up a video per second

how many bits is one byte

8

attributes of a vector graphic images

1. made up of geometric shapes

2. to edit the design its necessary to change each of the geometric designs

3. smaller file size

4. number of geometric shapes aren’t limited so are usually not realistic

5. svg,cgm,odg 

bit-map attributes

1. made up of pixels of different colours

2. possible to edit each of the pixels individually

3. file size is large

4. built pixel by pixel creates realism

5. jpeg,bmp,png

pros of a higher sample rate

1. larger dynamic range

2. better sound quality

3. less sound distortion

cons of a higher sample rate

1. larger file size

2. longer download/transmit times

3. requires greater processing power

audio compression def

lossy compression using perceptual music shaping (remove sounds outside of human hearing (20 to 20,000Hz)) MP3/MP4

how JPEG uses lossy compression

removes pixels based on the inability of the eye to spot certain colour changes and hues

RLE def

a lossless file compression technique used to reduce text and photo files in particular

how sampling is used to record a sound clip

the amplitude of the sound wave is first determined at the sampling rate

this gives an approximate representation of the sound wave

the sound wave is then encoded as a series of binary digits

bit rate

number of bits per second that can be transmitted over a network. it is a measure of data transfer rate over a digital telecom network