Sound Flashcards Preview

Computer Science > Sound > Flashcards

Flashcards in Sound Deck (7)
Loading flashcards...
1
Q

How is an image represented by pixels in binary format?

A

Images on a computer system are made up of thousands of small coloured dots, known as pixels (short for picture elements). Bitmap images are stored as an array of pixels. A black and white bitmap image will store a 1 for a black pixel and 0 for a white pixel.

2
Q

Why metadata needs to be included in an image file

A

The term metadata refers to ‘data about data’. Key properties that are needed to display an image correctly are stored as metadata. Data such as an image’s height, width and colour depth are typical examples of data stored in the metadata about an image. Without metadata, a computer system may render an image incorrectly on screen, such as displaying all pixels in one row.

3
Q

Character sets

A

In order to allow for data exchange between computer systems, character sets were devised. A character set is a table that maps a character with a unique binary number.

One such character set is the 7-bit American Standard Code for Information Interchange (ASCII). Part of the ASCII character set, that includes printable characters only, can be seen in the table overleaf.

4
Q

Data Structures

A

A data structure is a specific way of organising data within memory so that it can be processed efficiently. There will be a relationship between the data items that will vary according to the type of data structure being used.

5
Q

Static data type

A

A static data structure is designed to store a known number of data items. The values of the data can be changed but the memory size is fixed. An array is an example of a static data structure; we can change the values of the elements in the array but we cannot alter the memory size allocated to the array. Memory is allocated at compile time. As static data structures store a fixed number of data items they are easier to program, as there is no need to check on the size of the data structure or the number of items stored.

6
Q

Dynamic data structure

A

Dynamic data structures are designed to allow the data structure to grow or shrink at
runtime. It is possible to add new elements or remove existing elements without having to consider memory space. Memory is allocated at runtime. Dynamic data structures make the most efficient use of memory but are more difficult to program, as you have to check the size of the data structure and the location of the data items each time you use the data.

7
Q

What is an array

A

An array is a data structure that can hold a fixed number of data items, which must be of the same data type i.e. real, integer, string etc. The data items in an array are known as elements. An array is an example of a static list. The elements in an array are identified by a number that indicates their position in the array. This number is known as the index. The first element in an array usually has an index of 0.