What is metadata?
Data associated with a file that are used to reconstruct the original document, image or sound
What is a binary shift?
Moving the digits in a binary number left or right. Each time the value is shifted one place to the left number is multiplied by two each time the value is shifted one place to the right the value is divided by two.
What is a character set?
The set of characters that a computer can recognise based on their binary
The use of binary code to represent characters
Each press of a key on a keyboard, the computer registers as a binary code to represent each character
Why do computers need to come to an agreement as to which codes are used for each symbol?
Otherwise, computers will not be able to exchange information
What is a parity check?
Basic error detection method picks up corrupted bits
How many characters are available in ascii
128
How many characters are in extended ascii?
256
What is Unicode?
16 bit code to represent many additional non-English characters and a wide range of symbols
How many characters are available in Unicode?
2^16
What is ascii in relation to Unicode?
Ascii is a subset of Unicode
Equation for text file size
Number of characters times number of bits per character
How are images represented on screen?
A series of pixels
What is a pixel?
The smallest element of an image, they are stored in a computer as binary codes
What does the number of bits used for each pixel determine?
How many colours each pixel can represent
What is image meta data?
Image meta data contains information that tells the computer how to reproduce the image from the binary data stored
What is colour depth?
The number of bits used per pixel
What is resolution?
The number of pixels per unit of distance
What does a higher colour depth mean?
A large number of colours can be represented giving a better quality image. More data is stored making the image file larger
What does a higher resolution mean?
More pixels are used to represent the image meaning the quality is better and it can be made larger without losing resolution. More data is needed to represent the pixel meaning the file needed to store the data is larger.
What is the equation for image file size?
Colour depth x image height (px) x image width (px)
What are sounds?
A series of vibrations that continuously vary and can’t take any value they are analogue
How is sound stored on a computer?
Sound is sampled at regular intervals by a device that, convert analogue to digital signals, and the digital values are stored as binary
What is sample rate?
The number of samples taken per second measured in hertz
