Seeing, Hearing, and printing Data Chapter 4 Seeing, Hearing, and printing Data Mailto: kashif@pafkiet.edu.pk Web : www.Taleem.greatnow.com

Video and Sound

Monitors Most common output device Connects to the video card Categorized by color output Monochrome One color with black background Grayscale Varying degrees of gray Color Display 4 to 16 million colors

Monitors Cathode Ray Tube (CRT) Most common type of monitor Electrons fired from the back Electrons excite phosphor to glow Phosphor is arranged in dots called pixels Dot mask ensures proper pixel is lit

Monitors CRT color Phosphor dots arranged in triads Red, green, and blue dots Three colors blend to make colors Varying the intensity creates new colors Teaching tip Unless your students have spend a lot of time with HTML or graphics colors, they will have a hard time grasping how RGB values work. The best methods are to show them various colors and then let them experiment. The website www.lynda.com/hue.html provides decimal-value examples of RGB values. Once the students have seen different colors, open MS Paint and let the students develop their own colors. Challenge them to build pink, orange, brown and any of their favorite colors

Monitors CRT drawbacks Very large (16 inches deep) Very heavy (30 pounds) Use a lot of electricity

Monitors Liquid Crystal Display (LCD) Commonly found on laptops Desktop versions exist Solve the problems of CRT Fluorescent lights provide illumination

Monitors Passive matrix LCD Pixels arranged in a grid Pixels are activated indirectly Row and column are activated Animation can be blurry

Monitors Active matrix LCD Each pixel is activated directly Pixels have 4 transistors One each for red, green, blue One for opaqueness Transistors arranged in a thin film Animation is crisp and clean

Monitors Drawbacks to LCD More expensive than CRT Must sit directly in front of screen Can be more fragile than CRT Insider information The limited viewing angle can be an advantage. For high security systems, low viewing angles stop casual glances at the screen.

Monitors Paper-white displays Electro-luminescent displays (ELD) High contrast between fore and background Electro-luminescent displays (ELD) Similar to LCD Uses phosphor to produce light Plasma monitor Gas is excited to produce light

Monitors and Video Cards Monitors impacts user effectiveness Monitors should have Crisp text Clear graphics Adjustable controls Clear edges

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 Teaching tip It is helpful to draw the relationship between viewable and actual size.

Monitors and Video Cards Resolution Number of pixels on the screen.( (a) 640*480 (b) 800*600 (c) 1024*768 (d) 1152*864 (e) 1280*1024 Higher number creates sharper images Higher number creates smaller images Insider information Many CRT’s are capable of supporting several resolutions. LCD monitors in contrast often can only support one or two resolutions. The reason are the transistors on the LCD cannot move, while the electron gun on the CRT can simply aim for a smaller pixel. If you are in a computer class, stop and have students adjust their resolution on the screen. The simplest method is to right click the desktop and select properties. Click the settings tab, and adjust the slider. As the students are experimenting, have a student answer why larger resolution numbers make smaller images. The answer is higher resolutions draw with smaller pixels.

Monitors and Video Cards Refresh rate Number of time the screen is redrawn Modern equipment sets this automatically Improper settings can cause eyestrain Insider information Refresh rate is measured in Hz, or in cycles/sec. This means that if a monitore fresh rate is 100 Hz, it refreshes its pixels 100 tikes every second. Whenever a TV camera films a computer monitor, the monitor seems to have a line moving up the screen. This is the monitor refreshing the pixels. The camera films faster than the eye can see, which is why the refresh is noticeable.

Monitors and Video Cards 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 Insider information : When shopping for a color monitor, you should look for a dot pitch no greater than .28 mm. That number generally applies to 15-inch monitors.

Video Cards Device between the CPU and monitor Better cards result in better output Removes burden of drawing from CPU Have their own processor and RAM Modern cards have up to 512 MB RAM Capable of rendering 3D images Insider information The two leading video card families are ATI’s Radeon and NVIDIA’s GeForce line. Both offer exceptional graphics cards ranging from $50 to $600.

Ergonomics and Monitors Eyestrain Fatigue of the eyes Steps to avoid Choose a good monitor Place the monitor 2 – 3 feet away Center of screen below eye level Avoid reflected light If you can not avoid the reflection use an antiglare screen to reduce the reflection on the screen.

Ergonomics and Monitors Electronic magnetic fields (EMF) Generated by all electronic devices EMF may be harmfull to health Steps to avoid Keep the computer at arms length Take frequent breaks Use an LCD monitor Teaching tip Point out to the students that no conclusive study exists that directly list EMF as a cause of cancer, reduced muscle tone or reduced brain function. For more information see http://www.hhs.gov/ and search for EMF.

Data Projectors Replaced overhead and slide projectors Project image onto wall or screen LCD projectors Most common type of projector Small LCD screen Very bright light Require a darkened room

Data Projectors Digital Light Projectors A series of mirrors control the display May be used in a lighted room Insider information A projector is rated in lumens. This is a measure of how bright the projector is. Higher lumens ratings result in a brighter projector. For a guide to lumens ratings, see http://www.projectorpeople.com/tutorials/lumen-guide.asp.

Sound Systems Integral part of the computer experience Capable of recording and playback

Sound Systems Sound card Device between the CPU and speakers Converts digital sounds to analog Can be connected to several devices Modern cards support Dolby Surround Sound Insider Information Sound Blaster is the primary manufacturer of sound cards. Exceptional models start at around $30.00.

Sound Systems Headphones and headsets Replacement for speakers and microphones Offer privacy Does not annoy other people Outside noise is not a factor Headsets have speakers and a microphone Insider information The PS2 game SOCOM II Navy Seals includes a USB headset to allow verbal communication with other team members.

Printing

Commonly Used Printers Impact printers Generate output by striking the paper Uses an inked ribbon Non-impact printers Use methods other than force Tend to be quiet and fast Inkjet printers, for example, use tiny nozzles to spray droplers of ink onto the page.

Commonly Used Printers Dot matrix printers Impact printer Used to print to multi-sheet pages Print head strikes inked ribbon Line printers Band printers Speed measured in characters per second(cps)

Dot Matrix Print Head

Commonly Used Printers Ink-jet printers Non-impact printer Inexpensive home printer Color output common using CMYK Cyan, magenta, yellow, black Sprays ink onto paper Speed measured in pages per minute Quality expressed as dots per inch Insider information Nearly all of the electronics for the printer is kept in the ink cartridge. Thus, when the cartridge is replaced the printing components of the printer are replaced. Refilling cartridges is OK, but should not be reused more than 2-3 times.

Dots Per Inch

Commonly Used Printers Laser printer Non-impact printer Produces high quality documents Color or black and white Print process Laser draws text on page Toner sticks to text Toner melted to page Speed measured in pages per minute Quality expressed as dots per inch Insider information The laser printer works on a similar process to a photocopier. The first photocopier as we know it today was invented in Astoria NY in 1938 by Chester Carlson and Otto Kornei.

Commonly Used Printers All-in-one peripherals Scanner, copier, printer and fax Popular in home offices Prices are very reasonable

Comparing Printers Determine what you need Determine what you can spend Initial cost Cost of operating Image quality Speed 600dpi means 600 columns of dots and 600 rows of dots per inch. Printer speed is measured in the number of pages per minute (ppm)

High-Quality Printers Special purpose printers Used by a print shop Output is professional grade Prints to a variety of surfaces

High-Quality Printers Photo printers Produces film quality pictures Prints very slow Prints a variety of sizes Several models creat prints no larger than a standerd 4 * 6 inch snapshot, although newer photo printers can produce 8 * 10 inch or even 11 * 14 inch prints. Photo printers range in price from 200 dollar to 500 dollar.

High-Quality Printers Thermal wax printers Produces bold color output Color generated by melting wax Colors do not bleed Operation costs are low Output is slow

High-Quality Printers Plotters Large high quality blueprints Older models draw with pens Operational costs are low Output is very slow A roller plotter uses a robotic arm to draw with colored pens on oversized paper.Here, an architectural drawing is being printed.

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