Computing

• JPEG

  Joint Photographic Experts Group

  Lossy Compression

  Mostly Used For Photographic Images

  24 bit (true color)
• GIF


  Graphic Interchange Format

  Lossless compression

  8 bits allowing 256 colors

  Used for transparent images, logos animation, drawings
• PNG

  Portable Network Graphics

  Supports over 16 million colours

  Designed for Internet Transfer of Image

  Supports Multiple levels of transparency

  Pixels can be translucent Opaque or transparent
• SVG


  Scalable Vector Graphics

  Vector Graphics standard file format

  Does not lose quality when scaling

  Supports Layering

  Generally Smaller FIle SIze than Bitmapped Graphics
• WAV


  waveform

  used mostly for windows systems

  very uncompromising so high quality and large file sizes
• MP3

  Moving Pictures Group Layer 3

  uses different compression techniques to reduce size

  removes sounds our ears cannot hear
• MP4

  Moving Pictures group layer 4

  lossy compression

  small file sizes
• AVI


  High quality

  large file sizes

  Lossy and Lossless
• Firewall: A network security device that monitors and controls network traffic to and from a network. Helps to block out all security threats
• Network Security System

  Monitors and control incoming and outgoing traffic based on security rules which are predetermined
• Traffic Filter

  Filters traffic based on IP addresses, protocol, ports and other criteria allowing only authorised communication to pass through
• Monitoring Tool

  A firewall monitors network traffic identifying and logging potential security threats for further analysis
• Firewall Hardware is found in broadband routers
• Software firewalls are installed on your computer and are cusomtisable.
• Standby/Sleep

  RAM continues

  Data for software running is temporarily stored until user resumes work

  power to all other components is significantly reduced or turned off completely
• Hibernate

  Contents of RAM are copied to the hard disk

  Hard disk saves a permanent copy

  Hibernate can turn off almost all components off or down to a level of very low energy use
• PROS OF VECTORS

  Can be scaled without affecting quality

  Individual objects can be edited without affecting the rest

  Easily convert to bitmap

  Size of image can be increased keeping file size and quality the same
• CONS OF VECTOR

  difficult to be realistic

  dependant of hardware/software for appearance of quality
• PROS OF BITMAP

  Realistic

  Pixel level editing eg spray blur

  Same appearance regardless of hardware or software
• BITMAP CONS

  Scaling Causes pixelation

  ONly image as a whole can be edited

  Difficult to convert to vector

  Large File Sizes

  Increasing Image size need resampling and increases file size
• Laws of Computer Systems

  Computer Misuse Act

  Copyright Designs and Patents Act 1988

  UK GDPR

  Communications Act
• Computer Misuse Act

  Illegal to hack into computer systems

  Illegal to modify a computer system

  Illegal to interfere

  Making changes to a system to prevent others accessing it

  Making Changes to software of data
• Copyright designs and Patents Act

  Make unauthorised pirate copies of software

  Run pirate software

  Run multiple copies of software if only one was purchased

  Give Lend or Sell copies of bought software unless a licence to do so is granted
• UK GDPR

  Processed lawfully

  Used for declared purposes only

  Limited to declared purposes only

  Accurate

  Not held longer than necessary

  Held securely

  Data COntroller had accountability
• Communications Act 2003

  COvers against communications media

  Piggybacking - process of using someone else's internet access without their permission or intention to pay for access

  Protects against receiving threats online

  Illegal to send Offensive or indecent images or others
• Resolution- THe number of pixels making up the graphic
• Bit depth- the number of bits used to represent colours of shades of grey
• Memory is stored using unique addresses so the computer can read and write the data to the location correctly
• ALGORITHMS

  a set of steps you have to follow in order to complete a task
• What are the algorithms in nat 5

  Input validation

  Running total

  Traversing an Array