Karteikarten
Information Representation
Karten in diesem Stapel (13)
- 1ImagesBitmap Graphics :- A collection of bits that form an image.
- The image consists of a matrix of individual dots (or pixels) that all have their own colour.
Pixels :- These are small blocks of addressable area which have colours and these colours are represented by binary and stored as bits. - 2ResolutionImage Resolution - The amount of pixel an image contains per inch or centimeter.
Screen Resolution - The number of pixels a screen can hold. It is written as row by column ( row * column = total number of pixels ). Therefore, the higher the resolution the more pixels are available.
Colour depth - The number of bits used to represent a single colour on a pixel. - 3Vector GraphicsImages defined using mathematics and geometry (i.e points, lines, curves and shapes/polygons ). Objects and properties are stored mathematically.
- 4Sound-Sound are vibrations that travel through a medium.
-Sound waves are continuous in nature, which means there is infinite amount of detail for a sound.
-An analogue sound wave is picked up by a microphone and sent to an ADC in the form of analogue electrical signals. once the sound is converted into a digital form it can be stored and manipulated.
-Sound in analogue form can be represented by wave forms; the height of these waves can be sampled regularly with the height being represented by a bit-code. - 5Sound SamplingSampling Rate: -The number of samples taken per second.
-A higher sampling rate means that the waveform will be converted from analogue to digital form more accurately.
Sampling resolution: -Number of bits organised to each sample.
-The quality of a sound produced using a sound sampler depends on the sampling rate and sampling resolution.
-Like sampling rate, a higher sampling resolution means a larger file.
File size:-Bite rate -The number of bits used to store 1 second of sound.
-File size= sample rate * sample resolution * length of sound - 6File size-Bite rate -The number of bits used to store 1 second of sound.
-File size= sample rate * sample resolution * length of sound. This is the same as:
File size = Bit rate * length of sound. - 7Sound editing: features of a sound editing software-Recording
- Import and export
-Sound quality
-Editing
- Accessibility
-Effects
-Plug-ins
-Analysis
-Free and cross-platform - 8Video-Frame rate: -Frequency at which frames in a video sequence are displayed.
-Higher frame rate, better quality video = higher size.
-Interlaced (eg. 1080i): -Old technology (70 years ago)
-Each field of a video image displays every other horizontal line of a complete image therefore doubles FPS.
-Horizontal lines often visible due to distortion.
-Pros: -Refreshes faster, better visual smoothness and saves bandwidth.
-Cons: -Becoming outdated and interlaced screen will not show fast moving objects clearly.
-Progressive (eg. 720p)
-Execute every horizontal line simultaneously.
-Thus frame rate is the same as the number of individual pictures in a video sequence.
-This gives more detail in each frame.
-Pros: Crisp, detailed frames and is new and popular.
-Cons: Rough frame transition. - 9Compression Techniques-Lossless compression
-Lossy compression
-Temporal redundancy
-Spatial redundancy - 10Lossless compression-Breaks data into smaller form of transmission without losing data.
-Allows recreation of original.
-Run-length encoding: compression in which sequences with data value in many consecutive values are stored as a single data value and count. (eg. 0000134511111 can be written as [0-4]1345[1-5]). - 11Lossy compression-Compression loses file accuracy, generally smaller than lossless compression.
-Unable to get back original version.
-Eliminates unnecessary bits of data. - 12Temporal redundancy-Redundancy between frames.
-This is the correlation between adjacent data points.
-It is based upon abrupt transitions between frames. - 13Spatial redundancy-Redundancy by registering differences within a frame.
-An intercoded frame that is divided into macro blocks.
-Blocks are not directly encoded with raw pixel values.
-Encoder finds a block similar to the last frame.
-This frame is the reference frame.
-This process is done using algorithms.