Section 3 Flashcards
Binary base?
Binary has base 2 of just two numbers 0 and 1
0=off 1=on
State all the numbers of binary
1,2,4,8,16,32,64,128,256
Denary base?
Base 10, 0–9
Hexadecimal numbers
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
Hexadecimal base?
Base 16 numbers 0-F
What do the letters starting from A-F represent?
10,11,12,13,14,15
Binary to hexadecimal
Split eight bit binary into 2 parts and workout the 8421 number for each and put them together
Hexadecimal to binary
Do same as we would for the other way round except find values of them in binary
Decimal number into Hexadecimal
Divide the number by 16 for 1 hex number then use the remainder as the other hex number
Hexadecimal into decimal number
Multiply left number by 16 right number 1
Why use Hexadecimal?
Easier to remember and easier to read than binary
Hexadecimal is used to represent:
-Colour values in photo editing software and HTML
-MAC addresses
-Memory address locations in assembly language
Binary arithmetic
1+1=0 CARRY 1
1+0= 1 SAME OTHER WAY ROUND
0+0=0
1+1+1= 1 CARRY 1
ETC
Binary Shift
Is when a binary number and all its bits are moved a certain number of places left or right
A shift left is multiplied by 2
How many characters does an ASCII set have?
contains 128 each using 7 bits
What is Bitmap image?
made up of picture elements in pixels
What is a Pixel?
Represents smallest identifiable area of an image, each appearing as a square of a single colour
Image size
Width x Height
Colour depth
in bits per pixel
considering the number of colours
2 colours= 1 bit per pixel. 1 0
4 colours= 2 bit per pixel. 01 10 11 00
As number of bits per pixel increases so does the …….
However this significantly increases the …. ….
Quality(be able to see better with naked eye)
file size
How to calculate file size:
Width in pixels x height in pixels x colour depth
Dividing by 8 will give the size in bytes
Increasing number of pixels in image will also increase its ….
Size
Density of pixels in same sized area
Resolution
More pixels per inch(PPI)
the effect is
Smooth edges and improve overall quality
Increasing size of image file
possible to enlarge the image without visible loss of quality
improved resolution comes at the expense of either increasing the number of pixels in an image(increasing file size) or reducing the pixel size and therefore the visible size of the image
Analogue sounds
digitally recorded in binary
to record sound
amplitude or height of sound wave emitted must be measured and recorded at regular intervals
Frequency or sampling rate
How often height is recorded
bit depth or sample resolution
accuracy to which the height is recorded
affects file size and quality of sound played back
duration of recording affects the …. ….
File size
What is Sampling rate measured in?
Hertz(hz)
e.g. CD quality playback is recorded at 44.1 kHz
Compression software
Uses algorithms to remove repeated or unnecessary data
Advantages of compression software
-reduces size of file on disk (useful for when there are things like email attachment limits)
-useful for data over internet(smaller files transported in less time)-meaning takes less time to download
bitmap is uncompressed
Lossy compression
Lossy compression is a form of data compression that uses inexact approximations and partial data discarding to reduce the size of a file.
Lossy compression is used to store, handle, and transmit content more efficiently,
Lossless compression
Lossless compression is a type of media compression that shrinks a file’s size without any quality loss. A file shrunk with lossless compression is indistinguishable from the original.
Lossy formats
JPG, MP3, WMV, MPG
Lossless formats
TIF, PDF, GIF, PNG, MOV, ZIP
ADV Lossy
Smaller file sizes
Least transmission time
Reduces internet traffic and collisions
DISADV Lossy
Detail is permanently lost
Example Lossy
Music Streaming
Online images and Video images
Image libraries on devices or in the cloud
ADV Lossless
Original quality is preserved/no info loss
DISADV Lossless
Less significant reduction in the file size
Example Lossless
Text documents
Electronic books
High resolution print documents
Run length encoding(RLE)
Data particularly image data, can be represented using frequency/ data pairs. E.g. a black and white 5x5 image with a colour depth of i may be represented by the binary string:
00000111: represented as “five zeros three ones”
