Flashcards
Data represantation
Cards in this deck (25)
- 1BinaryBinary is expressed in a base 2 numerical system there are only 2 digits 1 and 0. 1 digit is called a bit, 4 bits is a nibble, and 8 bits are a byte.
- 2How to convert from Binary to Denary and Denary to Binary.Each bit represents a number. The more bits there are it is likely the larger the number. The first bit starts with 1 and we multiply by 2 ever time we move on to the next bit. So 1 would mean add the number it represents and 0 would mean don't. E.g. 10000100 = 132
- 3HexadecimalIt is a base 16 numerical system where a Hex digit represents a nibble in Binary.
- 4Uses of Hexadecimal- Used for HTML colours
- Error Messages
- MAC addresses - 5Why use Hexadecimal- It is much simpler and can represent an a byte of binary in 2 digits.
- Saves time and spaces as it a fewer amount of digits and easy to understand
- Easy to conver to binary or denary. - 6EncodingPractice of converting one type of data into another. E.g An image into a series of bindary numbers.
- 7BitmapIt is a method of encoding; i.e. representing/storing an image as binary. A bitmap is a pixel by pixel representation of an image. It can also be known as a raster.
- 8PixelSmallest addressable area that can be defined as a colour.
- 9Colour depthThe bits per pixel used to represent and encode colours. The more bits per pixel the more colours availble, resulting in a higher file size.
- 10Image ResolutionAmount of a pixels an image contains. Calculate by height x width. The higher the resolution the better the output quality.
- 11How to calculate the File size of an ImageImage resolution (height x width) x bits per pixel (Colour depth.)
- 12Storing sound- Sound is picked up by a recording device, i.e. a mircophone.
- It works by a magnet connected to the microphone
- Sound is represented by voltage changes.
- ADC converts it to a usable and savable sound. - 13Sampling- The ADC process is called sampling
- At regular intervals we measure the amplitude of the sound wave and then convert it; storing as a binary number.
- The number of times this done per second is called the sampling rate.
- Sample rates are in hertz( Hz) so 50,000 Hz means it was sampled 50000 times per second. - 14Resolution- The sound resolution/audio depth of a file is a the amount of depth we use to represent each sample.
- The more bits the finer the amplitude measure can be
- More bits also mean richer sound and a larger file size.
- Sound resolution has a larger impact than sampling. - 15Calculating file size for sound- Bit rate is the number of bits required to store a second worth of sound
- Bit rate = Sound resolution * Sample rate
- File size = Bitrate * Duratin of sound in seconds. - 16Binary Addition0+0 = 0
1+0 = 0
0+1 = 0
1+1 = 0 with 1 on the next column
1+1 + 1 = 1 with 1 on the next column - 17Overflow in Binary AdditionIf the sum of 2 positive numbers is too big for the provide space it become an overflow. The overflow flag on the CPU is raised. The CPU intterupts and sends an error message on the monitor or the program will crash. If it's 0 that is an extra number nothing will happen.
- 18Binary ShiftsShifting Binary is a quick way to multiply and divide Binary. When we divide it shifts right and for multiply it shifts left. Each bit we move represents multiplying or dividing by 2. E.g. /2^4 would mean shift to the right 4 times, and if it was to mean multiply then move to left 4 times by addig 0s.
- 19Two's complementA method to signify if a a number is negative. It's also a conversion system. When a Binary is converted using this a 1 would mean -ve and a 0 otherwise. The method works by leaving eveyrthing as it is until we pass the first 1. So all the bits after the 1st 1 will be flipped. I.e = 01010110 = 10101010.
- 20Binary Subtraction.
- 21Types of compression- Lossy
- Lossless - 22Lossy Compression- Discards unnecessary information
- In images subtle colour changes are averaged out and replaced, reducing colour depth.
- Repeated Compression can lost significant data
- Destrutive compression(irreverisible) - 23Lossless compression- Work by finding patterns and replacing instances of a pattern with a smaller token.
- Non destructive
- Used in Run length coding - 24File Maps (Bit map based)- BMP: Uncompressed & widespread portability
- GIF: 8 bit BPP, animated, simple Images, Lossless compression
- PNG: Range of BPP, Good for editing and creating images, lossless.
- JPEG: Good for web images, supports ranged of BPP, Lossy compression - 25What is Lossless/ Lossy most commonly used forLossy - Audio, Video, Images, etc
Lossless - Text, source code, etc.
Information
- Description
- Year 10 Computer Science (What I need for IGS) Flashcards on Data represantation, created by fiery Barbarian on 18/10/2021.
- Created by
- fiery Barbarian
- Views
- 0
- Rating