M150: Data, Computing and information. Outline Unit three. What’s next. Some questions. Your questions. 1- Unit three : Crossing the boundary: analogue universe, digital world. The world we live in. Analogue information: digital representation. Crossing the boundary. Going back.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
The world we live in.
Analogue information: digital representation.
Crossing the boundary.
What if? … changing the digital world.
Crossing the boundary – a final word.
A human connects with the world surrounding him using his senses.
A human’s imagination is a powerful tool of navigation between past, present, and future worlds.
The need of a human to reach out to the world is not fully satisfied by his senses since they have their limitations.
A computer’s role is to extend the human senses allowing him to grasp as much of the world as he would like.
A computer’s job is to:
All the interesting characteristics of the natural world.
Storage and presentation:
Once an aspect is captured it can be stored almost permanently.
Opening, copying, reviewing, or printing will not cause damage to the file.
Computers control a vast majority of appliances.
Exchange is done by attaching the files and sending them by email to different recipients.
With appropriate software, image manipulation is possible, corrections and modifications can be done to an image depending on the taste of the user.
Example of a manipulated image:
A photograph is a captured piece of reality from the world we live in.
For storage, we need to move a representation of this piece of reality to the computer world.
The boundary between the real world and the computer world is crossed.
It is the boundary between the analogue world and the digital world.
An analogue quantity is one that changes continuously (ex: analogue thermometer).
The temperature rises gradually from 14° to 15°, not by leaps.
An discrete quantity is one that changes in a series of clear steps (ex: discrete thermometer).
The temperature rises in a series of steps : 97.17 °, 97.18°, etc... What’s between these two numbers is simply ignored.
The terms discrete and digital are often used interchangeably.
A digital technology is one whose data may only have a finite number of discrete values.
The interior world of a computer is about numbers and nothing else.
A digital world is a world of numbers.
Working with numbers started with counting.
Counting starts from 1 and can go for ever.
Although there is an infinity of numbers there are only 10 fixed numbers or digits to play with.
0 1 2 3 4 5 6 7 8 9
After 9 there is 10, it is one group of ten plus zero, this number is written in two columns.
37 is three groups of ten plus seven.
345 requires three columns, it is three groups of hundred plus four groups of ten plus five.
Each additional column to the left will count as ten times bigger than the one on its right.
This is a base 10 arithmetic or a decimal system.
A computer only uses two digits 0 and 1, they correspond to tiny voltages in the computer’s memory.
1 represents 1.
10 is not ten, it represents one group of two plus zero.
100 is one group of four plus zero group of two plus zero.
Each additional column to the left will count as two times the column on its right.
This is a base 2 arithmetic, or a binary system.
A digit 0 or 1 is also called a bit (binary digit).
A byte consists of 8 bits, if we want to represent it pictorially it will look like this:
If a bit can only be 0 or 1 then the largest number stored in a byte would be:
And the smallest would be:
A word is a group of 4 bytes.
1 KB (Kilo Byte) consists of 1024 bytes.
1 MB (Mega Byte) consists of 1024 KB.
1 GB (Gega Byte) consists of 1024 MB.
1 TB (Tera Byte) consists of 1024 GB.
1 PT (Peta Byte) consists of 1024 TB.
Examples of other arithmetic systems:
Octal system or base 8.
Hexadecimal system or base 16.
A computer handles everything in a binary form, when taking a feature and passing it on to a computer it will endure a sort of transformation into numbers.
Word processors enable us to enter text into the computer, what we see as letters on the screen is in fact a series of numbers inside the computer.
Each character (alphabets, parentheses, accents, spaces, etc..) has its numerical representation in the computer.
Representations need to follow certain standards:
ASCII (American Standard Code for Information Interchange) standard which represent characters by a series of 7 bits (128 characters including uppercase and lowercase, punctuation marks, spaces, tabs, return carriage, etc…).
Unicode standard which represent characters on 2 bytes (16 bits) a total of 63 536 characters covering a much wider range than the ASCII standard.
When typing on a keyboard a program called BIOS (Basic Input/Output System) will transform the signal from the pressed button to its appropriate numerical code, other software will store it in memory.
Vision is the most dominant sense for a human being, a visual field includes light, colors, shade, form, etc…
Such features need to be transformed into numbers in order to cross the boundary and enter the computer world.
In the first painting, light and colors have a smooth look and effect.
In the second painting, light and colors have a grainy effect.
If we want to reduce an image into numbers we need to consider dividing it in a way similar to the second painting.
Take an image.
Put a border.
Divide it into equal sized squares.
If the square is entirely grey make it white.
If the square is entirely colored (mauve) make it black.
If the square contains both grey and color, if more than the third of the square is mauve then it will become black otherwise it will become white.
In the resulting image, the number 0 will be assigned if the square is white and the number 1 will be assigned if the square is black. We obtain a binary image, each mapped square is called pixel (picture element), such image transformation is called bitmap encoding.
One bit was allocated to each pixel in the image, 0 or 1, either black or white.
Allocating more than one bit will result in shades in between black and white.
2 bits will result in 11 black, 00 white, 01 light gray, and 10 dark gray.
More bits will result in more shades of gray, such mapping is known as grayscale.
Colors are represented in a different way.
Any color can be made out of a mixture of three basic shades Red, Green and Blue (R, G, B).
Each shade is represented by a byte (8 bits), giving values ranging from 0 to 255.
As a total we have 256 x 256 x 256 shades of color.
Red is (255, 0, 0) since it is all Red and 0 Green and 0 Blue.
Green is (0, 255, 255).
Blue is (0, 0, 255).
White is (255, 255, 255), all the color spectrum.
Black is (0, 0, 0), no color what so ever.
Shapes, line thickness, coordinates, all have their numerical representations in a computer.
In this picture the rectangle, the circle, the arrow, the line and the text area each has a number to define its type.
A Video or a movie, is a series of images that slightly differ one from another, passing them one after the other at a certain speed will give the illusion of movement.
A picture would be called a frame.
The speed of flipping the frames one after the other is called frame rate.
The process of digitizing an image consists into breaking it into squares.
The smaller the squares, the more accurate our representation of the analogue image will be.
Smaller squares will mean, more squares and therefore more bits to map them, which means more storage space.
Several formats exist for image digitizing, depending on the allowed loss of precision (ex: bmp, png, jpg, gif, etc…)
Hearing is the second most relied on sense for a human being.
A sound consists of a waveform.
Example of a waveform.
In order to digitize a sound waveform, we take samples of the sound at small time intervals, such a process is called sampling.
The number of times/second we take a sample is called the sampling rate.
The smaller the interval the better.
The process of digitizing a sound consists into sampling it and then associating a number to each sample (quantization).
The smaller the interval of taking the samples, the more accurate our representation of the analogue sound will be.
Smaller intervals will mean, more samples and therefore more bits to quantize them, which means more storage space.
Several formats exist for sound digitizing, depending on the allowed loss of precision (ex: mp3, wav, mid, etc…)
An image, video, or a sound is digitized and stored on the computer.
If we need to view an image or replay a sound we need some output devices.
The process consists of:
Identifying the suitable output device.
Arrange the numbers in a form suitable for the output device.
Interpret the code by the output device
Output devices for images:
Computer monitors (screen) :
CRT (Cathode Ray Tube) big box that looks like televisions.
LCD (Liquid Crystal Display) flat and thin.
Inkjet, work by firing drops of liquid ink on paper.
Laser, work by firing a laser beam and “burning” powder ink on paper.
Plotters are professional printers used by architects that work by moving a special pen on a paper.
Loudspeakers are the output devices for sound.
When outputting a video, the monitor (image output device) and the loudspeaker (sound output device) are used simultaneously.
Using appropriate software, computers will help you simulate what happens in the real world.
Simulations help us study problems through models or “maquettes” (ex: the earth’s climate).
Computer scientists will create a model, a simplification including only features directly affecting the system being modeled.
The GCM (General Circulation Model) is an atmospheric model.
The earth’s surface is divided into rectangular grids.
Each rectangle is divided into layers splitting the atmosphere into 3-D boxes.
Each box contains a sample number of points where temperature, pressure, humidity, wind speed, and other features are recorded.
The climate model needs to follow certain laws in order to be accurate:
The Navier-Stokes equations which relate the air movement to the earth’s rotation.
The thermodynamic equation which relates temperature variations to heat from the sun, condensation, and other sources.
Simulated prediction of weather patterns:
Human imagination associated with appropriate software will allow the creation virtual worlds in a computer memory.
An example is AlphaWorld, a virtual world where a virtual “you” a character you wish to be (avatar), could do any normal day things and also defy the laws of physics and fly.
Unit 4: Integrating data
Basic concepts about data and representations.
Signalling what’s important.
Text to hypertext.
Combining representations - hypermedia.
Beyond basic mark-up: introducing XML.
What are the two most relied on senses for a human being?
Define analogue, discrete, digital?
Give the binary representation of the following numbers 645, 1892?
What is a bit? What is a byte?
Name two Word Processors?
Who were the first people to take photographs?
Where was the first cinema located?
How did the photography and film industry evolve?
What is an output device?
Name a popular analogue model of the planet Earth?
Name a popular digital model of the planet Earth?
Name two games that give humans supernatural powers?