1.2.4 - Representing Flashcards

1
Q

What is a Character Set?

A

A defined list of characters recognised by the computer, with each character represented by a unique binary number

2
Q

What are the well known character sets? What’re the number of characters that can be represented?

A

ASCII - 7 bit set - 128
Extended ASCII - 8 bit set - 256
UNICODE - 24 bit set - >16mil

3
Q

How are images stored?

A

In Binary, as either
Bitmaps :
- Constructed from coloured squares called pixels
- Each pixel of a bitmap is stored in binary
Vectors :
- Stores the maths to draw coloured shape

4
Q

What are the number of bits required for a pixel?

A

Number required depends on the number of colours
- 1 bit has two values, so 1 bit can store two colours - black or white
- 2 bits have four values, so 2 bits can store four colours
- The number of bits for each pixel is the colour depth

5
Q

A
• Additional data stored with the image to define the width, height, colour depth/palette
6
Q

What is the effect on image size/quality when you change the colour depth/resolution?

A
• The greater the colour depth/res, the larger the file size
• The smaller the res, the lower the image quality
(pixels are larger in low res, less needed to fill the space)
7
Q

How is sound sampled and stored in digital form?

A
• Analog sounds are converted to binary
• Sample rate - takes measures of sound waves at regular intervals
eg. CD sampled at 44100Hz = 44100 samples taken per second
• Bit depth - affects the amount of info stored w each sample & helps the sound get as close to the original as possible
8
Q

How is the playback quality of a sound file affected by
a) Sample Rate
b) Bit Depth

A

a) More samples, more accurate sound
b) Larger depth, higher quality sound

9
Q

How is the size of a sound file affected by
a) Sample Rate
b) Duration
c) Bit Depth

A

a) The higher, the larger the file
b) Longer, larger file
c) The higher, the larger the file