CS100

Fundamentals of ICTFall 2014

Dr. Rehan Hafiz rehan.hafiz@seecs.edu.pk Lecture 04

Sensing, Hearing & Printing Data

Section-3A

Course Information, Credits & …

http://lms.nust.edu.pk/

Acknowledgement

A NUMBER of slides that follow are taken from the Lecture Handouts developed by

Sir Maajid Maqbool & Dr. Junaid Qadir& are being used with permission

& from Introduction to Computers, Peter Norton, 7th Edition

The graphic on the Title page has been taken from:http://www.getfilecloud.com/blog/wp-content/uploads/2014/01/building-blocks.jpg

Material from these slides CAN be used with following citing reference:

Maajid Maqbool, Junaid Qadir, Rehan Hafiz : Fundamentals of ICT 2014

Creative Commons Attribution--ShareAlike 3.0 Unported License.

Lectures: Monday (1400), Wednesday (1100)Lab: Thursday (0900) Shirazi/Database Lab-SEECSLab Engineer: Mr. Ahmed Shafqat <ahmed.shafqat@seecs.edu.pk>Contact: By appointment/Email: rehan.hafiz@seecs.edu.pkOffice: A311- Faculty Block, SEECS, Building

All images used in presentations are for educational purposes only. In most cases a hyperlink or image url is provided. If there is no reference and originator wishes image to be removed, then please send email to rehan.hafiz@seecs.edu.pk for compliance

What is an IMAGE ?What defines the quality of an image ?

Learning a bit more about images

•What is an image ?•A 2D array/matrix of data

•What is a pixel ?•The intensity value of a particular element of this 2D array/matrix

•Monitor Categories•Mono-Chrome•Grayscale•Color

•Monitor Types•CRT – Cathode Ray Tube•Flat Panal

PIXELPicture Element

• Value of each location is 0 or 1

• Mono-Chrome

How many different colors can you

represent using 24 bits ?

Monitors

•All monitors use some kind of technology to lighten up a display

A BIG monitor using multiple bulbs & Each bulb acting as a pixelIs this display monochrome, gray-scale or colored ?

Adding Colors

• Take THREE colored (R,G,B) BULBS and focus them on a region.

• The light will add up and a new color shall be formed depending upon the contribution of strength of R,G & B BULB

• Same principle used in Monitors

http://www.indiana.edu/~telecom/people/faculty/krause/graphics.html

Additive Color Model

• Additive Color is the color system used for computer graphics, TV and lighting design. This is the color mode used to create graphics for TV and web. It's referred to as additive since lights are mixed or combined to make the various colors.

• The primary colors (think of them as light sources) are:• Red

• Green

• Blue

• Mix them together and you get white.

CRT Monitors

• An Electron Gun fires a stream of electrons towards Phosphorous dots

• A Magnetic coil controls the horizontal & vertical deflection of the stream

• Phosphorous is a chemical that glows when bombarded with electrons

• The smallest number phosphor dots that the gun can focus is called a pixel

http://dc358.4shared.com/doc/FyEqNYnu/preview.html

CRT Monitors

• The electron gun systematically aims at every pixel on the screen.

• Raster Scanning

• Refresh Rate• The number of times per second

that the electron guns scan every pixel om the screen.

• Measures in Hz

• If Refresh Rate is lower the screen appears to flicker.• 72 MHz is a good refresh rate

http://dc358.4shared.com/doc/FyEqNYnu/preview.html

CRT Monitor

•Raster Scan• Black lines show each row of pixels• Blue lines show that we have drawn one image/frame on monitor

and now we are going to start the next image/frame• Hz – Number of frame refreshes per second !!

Color Pixel for CRT Monitor

• PIXEL = One group of Red, Green & Blue phosphor dots

• Three different beams for each colored dots

CRT Drawbacks

•Big•Heavy•Consume more power as compared with LCDs•Not Portable

Flat Panel Displays

•Liquid Crystal Display (LCD Displays)•Creates image with a special kind of Liquid Crystal that is normally transparent but becomes opaque when charged with electricity

•Drawbacks•Limited Viewing Angle •Difficult to work in bright light conditions

Common Types of Flat Panels

• Liquid Crystal Displays – LCD Displays• Fluorescent (Cathode) Backlight on a grid of Liquid Crystals

• Blacks are not that good

• Affordable flat panels

• Light Emitting Display – LED Displays• Actually a LCD panel with an LED Backlight instead of a fluorescent backlight

• Consumes less power

• Even thinner

• Blacks are better as compared to LCD

• PLASMA• Outputs lights on a screen

• Similar to a projection system, Colors are a bit washed out in bright light

• Higher response time

• OLED- Organic Light Emitting Diode – OLED Displays• A grid of LEDs all the way

• Very good Black

Resolution of Monitors PPI – Pixels Per Inch

• PPI stands for Pixels Per Inch and is a metric typically used to describe the pixel density (sharpness) for all sorts of displays, including cameras, computers, mobile devices, etc

http://www.ubergizmo.com/what-is/ppi-pixels-per-inch/

Comparing Monitors

•Size

•Resolution

•Refresh Rate

•Dot Pitch

•PPI

•Contrast Ratios•The difference between blacks & whites

Monitors and Video Cards

•Characteristics of good Monitors•Crisp text•Clear graphics•Adjustable controls•Clear edges

•What matters in a monitor•Size of screen•Resolution of screen•Refresh Rate•Dot Pitch•Aspect Ratio

Monitors and Video Cards

• Size of monitor• Measured in inches

• Measured diagonally

• Actual size• Distance from corner to corner

• Viewable size• Useable portion of the screen

• Resolution• Number of pixels on the screen

• Higher number creates

sharper images

Monitors and Video Cards

• Refresh rate• Number of time the screen is redrawn

• 75 hertz means 75 times per second

• Modern equipment sets this automatically

• Improper settings can cause eyestrain

• Dot pitch• Distance between the same color dots

• Ranges between .15 mm and .40 mm

• Smaller creates a finer picture

• Should be less than .22

Persistence of Vision

Persistence of vision is the theory where an afterimage is thought to persist for

approximately one twenty-fifth of a second on the retina,[citation needed] and believed

to be the explanation for motion perception, however it only explains why the

black spaces that come between each "real" movie frame are not perceived

Aspect Ratio

• Ratio between width and height

• Width divided by Height• 4:3 = 1.333

• 16:9 = 1.777

• What is aspect ratio of a Full HD monitor ?

• 1920 x 1080 so Aspect Ratio?

CS100

Fundamentals of ICTFall 2014

Dr. Rehan Hafiz rehan.hafiz@seecs.edu.pk Lecture 04

Interacting with your Computer

Section-2A & B

Section 2A

• Keyboard

• The Mouse• Trackballs• Trackpads• Pointers

• Ergonomics & RSI

• Other input devices• Pens & Touch Screens

• Optical Input Devices• Bar Code Reader• Image scanners & OCR (Optical Character Recognition)

• Audiovisual Input Devices• Microphone – (Uses Sound card), Audio Calls, Recording, Skype• Video Input- (Webcams), Video Conferencing• Video Capture Cards• Digital Cameras

Bar Code Reader

Laser BeamLight Sensitive Detector

Good Resources:https://www.denso-wave.com/en/adcd/fundamental/barcode/scanner/http://www.carolinabarcode.com/how-barcode-scanners-work-a-69.html

Scanners

• Image Scanners convert printed image into electronic form by shining light onto the image and sensing the intensity of light at every point

Scanners

•ResolutionA scanner's optical resolution is determined by how many pixels it can actually see. For example, a typical flatbed scanner will use a scanning head with 300 sensors per inch, so it can sample 300 dots per inch (dpi) in one direction.

http://www.nuance.com/scannerguide/firsttimeusers/specifications/resolution.asp

OCR : Optical Character Recognition

•When a scanner scans a page, the image is stored as a bitmap(Image).

•Job of OCR is to EXTRACT text that a computer can understand

Learn to Find ProblemsA CS graduate finds solution for local problems

Photo Credits: http://www.jawbologna.com/wp-content/uploads/2014/03/idea.jpg

Resolution of ImagesDPI – Dots Per Inch

https://cyberdog.wikispaces.com/file/view/Resolution-Happy-Faces.png/298646830/Resolution-Happy-Faces.png