2.6 Data Representation Flashcards
What is the order of data size?
Bit - single digit (0 or 1) Nibble - 4 bits Byte - 8 bits Kilobyte - 1024 bytes Megabyte - 1024 KB Gigabyte - 1024 MB Terabyte - 1024 GB Petabyte - 1024 TB
How do computers understand binary?
They don’t understand the numbers 1 and 0, they understand flashes of electricity that pass through the transistors.
1 = Electricity pulse
0 = No electricity pulse
What number system is binary?
Base 2:
2 possibilities - 1 or 0).
Define vector
An image drawn by a set of mathematical formulas and can be scaled infinitely without any loss in quality.
Every line and shape has a value that changes when the image expands.
Define bitmap
Page is divided into an invisible grid and each pixel is assigned a colour in binary (colour depth).
Higher bit depth = Higher image quality.
What is PPI and DPI?
Pixels per inch.
Dots per inch.
What happens if a pixel is to represent more than 1 colour?
We need to use more bits to make a range of colours available.
How do you find out how many bits represent colours?
2 to the power of the number of bits = number of colours.
1 bit = 2 colours.
2 bits = 4 colours.
3 bits = 8 colours.
What happens with greater colour depth?
The more:
Realistic colours there are
Data needs to be stored.
File size on the disk is needed.
What happens with higher resolution?
There are more pixels, higher quality and higher image file size.
What is digital sound broken down into?
Thousands of samples per second - each of which are stored as binary data.
What does the quality of the samples depend on?
1) Sample frequency.
2) Sample size / bit depth.
3) Bit rate.
Define sample rate
No. of audio samples captured every second.
Define analogue
Made up of a variation of dynamic and frequencies.
Define sampling
Recording snippets of sounds at set intervals.
Define character set
The possible characters that can be represented in a computer system.
E.g. ASCII and Unicode.
Define metadata
Image data that allows the computer to recreate the image from the binary data in the file.
Examples: Dimensions. Number of bits per pixel. Location. Data and File type.
Define image size
Width and height of a bitmapped image, measured in pixels.
If an image has its colour depth increased what is the effect?
The file size is bigger.
Define overflow error
When the binary number is too big than actually possible
What are the hexadecimal numbers compared to denary numbers?
A = 10 B = 11 C = 12 D = 13 E = 14 F = 15
Define lossy compression
The file is compressed and data is lost. It compresses more than lossless
Should be used in audio files.
Define loseless compression
The file is compressed; no data has been lost (file size is just smaller, but it isn’t as compressed as lossy ).
Should be used in text documents.
What is the effect of multiplying the binary number by 2?
The number is shifted to the left by 1 bit
What is the effect of dividing a binary number by 2?
The number is shifted to the right by 1 bit
Define underflow
When the binary number is too small than actually possible
