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48 Cards in this Set
- Front
- Back
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Bit, nibble, byte |
1 bit is the smallest available value 4 bits in a nibble 8 bits in a byte |
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Binary Addition Rules |
0+0 = 0 0 + 1 = 0 1 + 1 = 0 carry 1 1 + 1 + 1 = 1 carry 1 |
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Binary Subtraction |
Find the opposite of then second number, add 1 then add it to the first number. Put the left over 1 in brackets at the front |
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When doing binary to hex... |
Split the byte into 2 nibbles and find the value of each nibble |
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When doing hex to denary... |
Find the binary first, then change it from binary to denary |
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Check digit |
• The last number of an ISBN number or barcode • Used to make sure the barcode or ISBN number is correct and has not been tampered with, broken or faked. • Steps 1) Multiply the first digit by 1 2) Multiply the next digit by 3 3) Multiply the third digit by 1 4) Continue until you've done all the numbers but the last number 5) Add all the new values together 6) Find the lowest multiple of 10 above the sum of the values 7) Do multiple of 10 minus the sum 8) The answer should be the final number of the barcode or ISBN number (the check digit) |
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ASCII |
• American Standard Code for Information Interchange •The most common format for text files in computers and on the internet •A character set •Each alphabetic, numeric or special character has a corresponding 7-bit binary or 2 digit hexadecimal value •The ASCII character has a maximum of 128 value (the delete key) |
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Sample |
1 piece of data which represents how a sound should sound |
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Bit Rate |
The number of bits transferred per second (of audio) |
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Resolution |
* The number of pixels contained on a display monitor * The number of pixels in a given area on a screen/monitor * The number of dots/pixels per inch or centimetre *It is not the number of pixels that determine the sharpness of an image but the size of each pixel *The smaller the pixel, the better and sharper the image |
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Pixel |
The basic unit of programmable color on a computer display or in a computer image, the physical size of a pixel depends on how you've set the resolution for the display screen |
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Metadata |
Data that describes other data by summarising basic information about data, which can make finding and working with particular instances of data easier |
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Binary |
A number system with base 2, mostly used by computers |
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Denary |
A number system with base 10 |
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Hexadecimal |
A number system with base 16, it uses numbers and letters |
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Compression |
The process of reducing the size of a data file Shortens download times Two types: lossy and lossless |
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Colour Depth |
The number of bits used to represent the colour or greyscale value of a single pixel in a bitmapped image 2 to the power of colours = bits Colours to the power of 1/bits = 2 |
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Binary Shift |
A binary shift is an operation done on all the bits of a binary value in which they are moved by a determined number of places to either the left or right |
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Analogue |
A device or system that represents changing values as continuously variable physical quantities |
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Digital |
Electronic technology that generates, stores, and processes data in terms of two states: positive and negative. Positive is expressed or represented by the number 1 and non-positive by the number 0 |
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How Does Resolution Affect An Image? |
If the resolution is low, the picture isn’t very clear and you can see the pixels |
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How Is Colour Coded? |
*The colour of a single pixel is coded using the RBG colour model *Relative brightness of red (R), green (G) and blue (B) are encoded separately *In an 8 bit colour system it goes RRR GGG BB *On computers, there are usually 32 bit colour values *They go RRRRRRRR GGGGGGGG BBBBBBBB TTTTTTTT (T = Transparent) |
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How does colour depth affect an image? |
The higher the colour depth, the more colours available for the picture |
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Bitmap |
Created when the pixels of an image are mapped to positions in memory Colours are stored as binary codes |
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Visual Display Unit (VDU) |
* An output device which displays information in pictorial form and input signals as characters on a screen. * It is divided into pixels which represent the images stored in memory. * For example a computer monitor. |
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Overflow |
An overflow error is when the sum is a 9-bit binary value and so it is too big for the system. This means that the 9th digit (256 value) must be removed and so data is lost. |
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Unicode |
*An international encoding standard *Used with different languages and scripts *Each letter, digit, or symbol is assigned a unique hexadecimal value that applies across different platforms and program *Has thousands of different combinations |
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ASCII vs Unicode |
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Examples of Metadata |
*Author of the data *Time and date of data creation *Time and date of data modification *Location on the computer network *Location photo was taken |
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Calculating minimum file size |
minimum because it doesn't include meta data |
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How do the resolution and colour depth of images affect their file size? |
*The higher the resolution, the bigger the file size of the image *The higher the colour depth, the more colours available for the picture and the bigger the file size of the image |
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Analogue Sound |
Continuous changes in air pressure |
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Digital Sound |
Discontinuous (1s and 0s) samples of sound made by measuring an analogue sound at set intervals in a process called sampling |
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Sampling Rate |
The number of audio sample measurements taken at fixed and regular intervals (each second) |
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How is sound converted from analogue to digital? |
*Measurements of analogue sound are taken at fixed and regular intervals (each second) and the sounds’ volume and pitch at that interval is recorded *Measured in Hertz (Hz) -1 Hz is 1 measurement per second -A CD uses 44,100Hz so there are 44,100 measurements per second |
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How do the sample size, bit rate and frequency affect a digital sound file size? |
Sample Size -If each sample is bigger, then the digital sound file size will also be bigger Bit Rate -If there are more bits being processed per second, then the digital sound file size will increase Frequency -If you increase the frequency, the the digital file size will increase too. |
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Lossy Compression |
*Removing data that is the least likely to be noticed by the human eye or ear from a file to make it smaller *A file compressed using lossy compression cannot be restored to its original condition *In photographs, it is the the only method that can achieve significant file reductions because the sequence of pixels is unpredictable *In music, songs that are too high pitched and too low pitched (top and bottom 20%) are lost *Lossy compression uses inexact approximations and partial data discarding to represent the content to reduce data size for storage, handling, and transmitting content |
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Lossless Compression |
*Compressing a file without losing any of the information in the file *Enough information must be stored about a file so that it can be recreated later *All the data is packed into a smaller space and it can then be unpacked |
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JPEG |
*Stands for Joint Photographic Experts Group *A file format which is used to compress digital images *When you take a picture on a camera and you transfer it onto a computer, it becomes a jpeg because it needs to be compressed to fit onto the hard drive *It is lossy (the unnecessary data is discarded) *You can usually choose how much compression you want (compression factor) |
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GIF |
*Stands for Graphics Interchange Format *A lossless format for image files that supports both animated and static images *Only suitable for small images such as logos with a limited number of colours *Image files that are compressed to reduce transfer time *An image which contains a number of images or frames compressed into a single file *Has 8 bits |
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PNG |
*Portable Network Graphics *A graphics file format that supports lossless data compression *Created as a non-patented replacement for GIFs *Supports palette-based and full colour non-palette based images with palettes of 24-bit RGB or 32-bit RGBA (alpha) colors and grayscale images (with or without alpha channel for transparency) *Alpha compositing is the process of combining an image with a background to create the appearance of partial or full transparency |
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BMP |
*Graphics image file format used to store bitmap digital images *It is uncompressed (raw) *Commonly used as a simple graphics file format on Microsoft Windows platform |
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Sound Graphs |
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How do you estimate the file size for a sound file? |
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MP3 |
*Standard file of listening to and distributing digital music nowadays *Uses lossy compression to reduce files to a tenth of the original *Removes parts of recordings that are deemed unrecognisable to the human ear |
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*Portable Document Format *An open standard for exchanging documents *Lossless compression *Text and graphics are displayed exactly as in the original, with no need to have the software that created the original document *Many applications are capable of reading or creating PDF documents |
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MPEG |
*Moving Pictures Expert Group *A set of standards designed to encode audio-visual components *Uses lossy compression for both the sound and visual components *Various versions of MPEG are used for digital transmissions via cable and satellite and for terrestrial digital channels *Used to encode DVD movies *Can be decoded by most domestic audio-visual equipment |
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32 Bit Colour Wheel |
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