Chapter 1 (Abigail) Flashcards
Data
Raw facts and figures with no meaning attached
Information
Data with meaning
Number system of which computers store data
Binary System
Smallest unit of storage, has a value of 0 or 1
Binary digIT (bit)
ASCII meaning
American Standard Code for Information Interchange
Integer Numbers
Numeric data type- a whole number which can be positive or negative
Real Numbers
Numeric data type- includes whole numbers (integers) as well as numbers with decimal and fraction parts.
Long Date
Date/ Time type- Saturday, April 1, 2018
Medium Date
Date/ Time type- 1 Apr 2018
Short Date
Date/ Time type- 01/04/2018
Long time
Date/ Time type- 13:26:34
Medium time
Date/ Time type- 01:26PM
Short time
Date/ Time type- 13:26
What is a character?
A single letter or digit represented by codes from the character set used by the computer (e.g. ASCII)
What is a string?
Textual data in the form of a sequence of characters from a character set. This could be in the form of a word. A string will have a variable number of characters
Arrange in ascending order: a nibble, a megabyte, a byte, a terabyte, a kilobyte, a bit,
A bit, a nibble, a byte, a kilobyte, a megabyte, a gigabyte, a terabyte
What is a pixel?
The smallest unit of a digital image that can be displayed & edited on a computer screen. Each pixel can have its own individual colour and, together, a large group of them can make a complete image.
What is image resolution and how is it represented?
Image resolution describe the quality of an image. The greater the number of pixels used in an image, the higher the image resolution and the sharper the image. However, higher resolution images require more storage space. Image resolution is represented by 2 numbers, e.g. 1280 x 720. The first number is the amount of pixels displayed horizontally while the second is the number of pixels displayed vertically.
What are bitmap graphics?
- Made from a grid of pixels
- E.g photo on a phone or a computer scan
- Higher resolution= Higher quality
- Take up a lot of storage space as bitmap graphics store details about every single element (pixels) of the image
- Can be compressed to reduce file size but this can result in loss of quality.
- Pixelation can occur when the bitmap image is enlarged too much
What are vector graphics?
- Images made from mathematical components, e.g. curves and shapes, instead of pixels
- Components can be edited separately
- Require less storage capacity as they store information about the shape of individual components rather than using pixels.
- Meaning they can be saved as smaller files and edited without a loss of quality when enlarged
- Used for the likes of logos
What is streaming?
A process which allows video to be viewed on a website or all straight away, without having to wait for the full video to be downloaded.
What is a buffer?
An allocated part of memory that is used to store a downloaded part of a video before it is watched. When a user is watching a video, a buffer is used to download the next part.
What is sample rate?
The number of audio sound samples captured every second to represent the sounds digitally & is measured in Hertz (Hz). The more samples taken, the more accurate the sound wave which results in better quality audio.
What is bit depth?
The number of buts used to store each sound sample. Higher quality sound requires more depth.
What is bit rate?
Refers to the quality of data measured in bits that is processed in a given amount of time. Usually recorded in kilobits per second.
What is data portability?
The ability to transfer data from one computer to another or from one software application to another without having to re-enter the data.
Describe a JPEG:
-Stands for Joint Photographic Expert Group
-A JPEG is an image file
-Can be compressed
Describe a TIFF:
-Tagged Image File Format
-Stores bitmap images
-Allows the image to be portable
Describe a PNG:
-Portable Network Graphics
-Image File
-Can be transparent
-Allows data compression of bitmapped graphics.
Describe a PICT:
-Image File for Apple Graphics
-Supports graphic interchange between both bitmapped & vector graphics
Describe a GIF:
-Graphics Interchange Format
-Bitmapped Image File
-Can be animated
Describe a TXT:
-Plain text document
-Text file
Describe a CSV:
-Comma-Separated Value
-Text file
-Often used for moving tabular data t between a spreadsheet & a database.
Describe a RTF:
-Rich Text File
-Used to text-based documents
-Allows the movement of text files between different word processors
Describe a MP3:
-Sound File
-Compresses sound to decrease file size for storage.
Describe a MP4:
-Compresses both sound & video
-Allows data for streaming across the internet
Describe a MIDI:
-Musical Instrument Digital Interface
-Sound file
-Allows samples to be interchanged between different digital musical instruments
Describe a MPEG:
-Motion Pictures Expert Group
-Video type
-To do with the compression of video
Describe an AVI:
-Audio Video Interleaved
-Multimedia file format
-Can contain both audio and video content
Describe a PDF:
-Portable Document Format
-Can be created from a wide range of files (e.g. Microsoft Word & PowerPoint)
-Usually read only
Describe a WAV:
-Windows Audio Waveform
-Stores an audio bit stream
-Uncompressed
Describe a WMA:
-Windows Media Audio
-Audio data compression file
-Developed by Microsoft for Windows Media Player
What is data compression?
Data compression is used to convert digital data to as small a size as possible. Compressed data takes less time to load.
What is Lossy Compression?
Lossy compression reduces file size by permanently removing some of the data (eg reducing the amount of colours in an image) this data is permanently lost. This can result in reduced image quality. An example of lossy compression is a JPEG.
What is Lossless Compression?
Lossless compression maintains the file’s quality so that no data is lost. An example of this is using WinZip software which reduces file size by ‘“zipping” up a file so it can be sent over the internet. The file can then be “unzipped” exactly as it was before it was compressed.
What is an analogue signal?
A continuous varying signal that represents a physical quantity.
Why does an analogue signal need to be converted to digital?
So that the computer can process it.
What will an analogue to digital converter do?
Sample a sound wave at regular time intervals. If the number of sound samples per second (sample rate) is lower then the digital wave will be less accurate.
