Data Representation

Question 1

What is the only type of data the CPU can store and process?

Answer 1

Binary

Question 2

Why is it important for us to have a universal text system?

Answer 2

To allow all computers to use the same codes to represent the same characters
Only have to learn one code to work on many computers

Question 3

Give an example of a ASCII code and what it represents

Answer 3

65 = A
97 = a
etc

Question 4

Give an advantage of

a) Unicode compared to ASCII
b) ASCII compared to Unicode

Answer 4

a) Larger range of characters can be represented

b) Smaller storage requirements

Question 5

Describe ASCII

Answer 5

ASCII(American Standard Code for Information Interchange) is a system used to represent characters. It stores each character in 8 bit code.

Question 6

Why do computers use base 2 instead of base 10?

Answer 6

Base 2 is ideal for storing binary numbers

Base 10 requires a lot of processor space to build in rules for arithmetic such as addition,subtraction

Question 7

How are integers stored in a computer?

Answer 7

Each integer has an individual binary number.

Question 8

How many values can be represented by 5 bits?

Answer 8

2^5

Question 9

What is the range of values that can be stored in 18 bit?

Answer 9

0 to 2^18 - 1

Question 10

How can negative integers be represented on a computer system?

Answer 10

Two’s complement

Question 11

How do you represent floating point numbers in a computing system?

Answer 11

Floating Point Form

Question 12

If you allocate more bits to storing the<em> mantissa <em> of a floating point number, what will happen?</em></em>

Answer 12

The precision of the number will increase

Question 13

How would you increase the range of a floating point number?

Answer 13

Allocate more bits to the storage of the exponent

Question 14

Describe a bit-map image

Answer 14

A bit-map image is where the image is stored as a 2D array of pixels where each pixel can be individually edited. The colours in the picture are each a unique binary number.

Question 15

What is the definition of ‘bit depth’

Answer 15

Bit depth is the number of bits used to store each pixel

Question 16

If you increase the <em>resolution</em> of a picture, what are you increasing?

Answer 16

The number of pixels in a defined place

Question 17

What is an advantage of storing your image as a bitmap rather than a vector?

Answer 17

<ul>
<li> Able to individually edit pixels</li>
<li>Able to do red eye removal</li>
</ul>

Question 18

Describe how images are stored as vector images

Answer 18

In vector images, the image is stored as a series of vectors which describe the attributes of the objects in the image. For example, the vectors of a circle could relate to fill colour, line thickness, radius, centre(x,y) etc

Question 19

If the bit depth is represented by <strong>n</strong> , what would be the number of colours?

Answer 19

2^n

Question 20

Describe advantages of storing your image as a vector rather than a bitmapped image

Answer 20

<ul>
<li> Able to layer objects </li>
<li> Able to resize and rotate individual objects</li>
<li>Resolution Independant</li>
</ul>

Question 21

What are advantages to compressing your images?

Answer 21

<ol>
<li> Faster file transfer speed </li>
<li>Less memory required to store images</li>
</ol>

Question 22

Give an example of a file type that uses lossy compression

Answer 22

JPEG

MP3

Question 23

Give an example of a file type that uses lossless compression

Answer 23

GIF

Question 24

Describe how Discrete Cosine Technique reduces file size and state what type of compression it is

Answer 24

Discrete Cosine Technique is a LOSSY compression technique that <strong>applies a mathematical formula </strong> based on the cosine wave to groups of <strong> 64 </strong>pixels (8 x 8)

Question 25

Lauren has a picture of the Swedish Flag she would like to send to her friend. What form of compression should she use to ensure it has a fast data transfer speed?

Answer 25

She should use RLE(Run Length Encoding) as the Swedish flag has runs of repeating colours which she could save as the colour and how long the run is