Chapter 1 - Information Representation And Multimedia Flashcards
What are natural numbers?
Any whole number, starting at 0.
What are integers?
Whole numbers that can be negative.
What are rational numbers?
Any number that can be expressed as a fraction or ratio.
What are irrational numbers?
Numbers that can’t be expressed exactly as a fraction.
What is a real number?
A number that is rational or irrational.
What is an ordinal number?
A number used to describe the position in which values appear.
Why is hexadecimal used?
A hexadecimal value is much easier to read and remember than a string of binary digits. It is quicker to write or type, since a hex digit takes up only one character, not four. There is less chance of making an error when typing hex characters than a string of 1s and 0s. It is used to define colours, in MAC addresses, in assembly languages and machine code. It is very easy to convert to and from binary.
What is a character?
A character or symbol that is present on the keyboard. It has a specific character code that consists of numbers.
What is a character set?
A list of characters that have been defined by computer hardware and software. It is necessary to have a method of coding, so that the computer can understand human characters.
How many bits does an ASCII character use?
7.
How many bits does Extended ASCII use?
8.
How many bits does unicode use?
8 to 32.
What is a bitmap image?
Bitmapped graphics are created using a grid of pixels. Each pixel is given a colour value.
What are vector graphics?
Vector images are made up of geometric shapes or objects rather than by manipulating individual pixels. The properties of each shape are stored and retrieved in order to mathematically redraw the shape on the screen to display it.
How does analogue to digital conversion work?
Analogue sound samples are recorded via an amplifier. Each sample is quantised to measure its wave height and translate this into an integer value. The integer value is then converted and stored digitally as a binary value. To output a sound, the reverse happens.
What is the sample resolution?
The number of bits (audio bit depth) used to record each measurement is known as the resolution.
What effect does sampling rate have?
The frequency or sample rate per second affects the level of detail in the digital representation.
What is the file size of a sound file?
File size = sample rate × resolution × length in seconds.
What is the Nyquist Theorem?
There is a limit on the lowest sampling rate (f_s) that can be used for an accurate recording. Because sound is made up of many components each at different frequencies, samples must be twice the highest frequency in order to replicate the original sound wave. f_s ≥ 2f_max.
What is image compression?
Image compression is the reduction in file size to reduce download times and storage requirements.
What is lossless compression?
When the file is compressed, the quality of the image remains the same. The image can be reconstructed into its original form. In this case, information is very important and cannot be lost.
What is lossy compression?
When a file is compressed, the unnecessary bits of information are removed permanently. This information is less likely to be noticed by humans. This type of compression is used for photographs where the information to be compressed cannot be predicted.
What is run-length encoding?
Run-length encoding (RLE) is an example of a compression algorithm that converts consecutive similar values into code. This code consists of the identical value and the number of times this value is repeated. This is a lossless type of compression.
What is binary?
A base two number system based on the values 0 and 1 only.
