Data Representation Flashcards
What is the only type of data the CPU can store and process?
Binary
Why is it important for us to have a universal text system?
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
Give an example of a ASCII code and what it represents
65 = A
97 = a
etc
Give an advantage of
a) Unicode compared to ASCII
b) ASCII compared to Unicode
a) Larger range of characters can be represented
b) Smaller storage requirements
Describe ASCII
ASCII(American Standard Code for Information Interchange) is a system used to represent characters. It stores each character in 8 bit code.
Why do computers use base 2 instead of base 10?
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
How are integers stored in a computer?
Each integer has an individual binary number.
How many values can be represented by 5 bits?
2^5
What is the range of values that can be stored in 18 bit?
0 to 2^18 - 1
How can negative integers be represented on a computer system?
Two’s complement
How do you represent floating point numbers in a computing system?
Floating Point Form
If you allocate more bits to storing the<em> mantissa <em> of a floating point number, what will happen?</em></em>
The precision of the number will increase
How would you increase the range of a floating point number?
Allocate more bits to the storage of the exponent
Describe a bit-map image
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.
What is the definition of ‘bit depth’
Bit depth is the number of bits used to store each pixel
If you increase the <em>resolution</em> of a picture, what are you increasing?
The number of pixels in a defined place
What is an advantage of storing your image as a bitmap rather than a vector?
<ul>
<li> Able to individually edit pixels</li>
<li>Able to do red eye removal</li>
</ul>
Describe how images are stored as vector images
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
If the bit depth is represented by <strong>n</strong> , what would be the number of colours?
2^n
Describe advantages of storing your image as a vector rather than a bitmapped image
<ul> <li> Able to layer objects </li> <li> Able to resize and rotate individual objects</li> <li>Resolution Independant</li> </ul>
What are advantages to compressing your images?
<ol>
<li> Faster file transfer speed </li>
<li>Less memory required to store images</li>
</ol>
Give an example of a file type that uses lossy compression
JPEG
MP3
Give an example of a file type that uses lossless compression
GIF
Describe how Discrete Cosine Technique reduces file size and state what type of compression it is
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)
