Alternate Input Devices
Few Basics: Input Devices
Devices for the Hand – Pen
Tablet PCs, PDA
Pen used to write data
Pen used as a pointer
Handwriting recognition is difficult
On screen keyboard
Not used for inputting large volume of data
Touch Screens
accept input by allowing the user to place a fingertip directly on the computer screen
Use sensors to detect touch
Well suited for simple applications
- ATM
- Public information kiosk
work well in environments where dirt or weather would render keyboards and pointing devices useless, and
where a simple, intuitive interface is important.
Touch screens have become common in
- fast-food restaurants,
- department stores,
- drugstores, and supermarkets,
- where they are used for all kinds of purposes, from creating personalized greeting cards to selling lottery tickets.
Game Controllers
Enhances gaming experience
Provide custom input to the game
Modern controllers offer feedback
Two broad Categories
- Joystick
- Game pad
Joystick
Around for long time
Can be used other than games
enable the user to “ fly” or “ drive” through a game, directing a vehicle or character
popular in racing and flying games
One variant is the racing game controller, which includes an actual steering wheel
some racing game controllers even include foot pedals and gearshifts
Game Pad
is a small, flat device that usually provides two sets of controls— one for each hand.
extremely flexible and are used to control many kinds of games
If you do not have a joystick, you can use a game pad to control most racing and flying games.
Many computer games still provide support for a mouse or keyboard, so a dedicated game controller is not always required
Optical Input Devices
Allows the computer to see input
Bar code readers
- Converts bar codes to numbers
UPC Universal Product Code
- Computer find number in a database
- Works by reflecting light
Amount of reflected light indicates number
Bar Code Reading Process
reader emits a beam of that is reflected by the bar code image
light-sensitive detector identifies the bar code image by recognizing special bars at both ends of the image
special bars are different, so the reader can tell whether the bar code has been read right-side up or upside down
After detector has identified the bar code, it converts the individual bar patterns into numeric digits code the computer can understand
reader then feeds the data into the computer
Image Scanners
Converts printed media into electronic
Reflects light on the image
Sensors read the intensity
Filters determine color depths
How an Image is Scanned
A light source is moved across a printed page
The light bounces off the page and is passed through a lens
And onto the light sensitive diodes which converts light to electricity. There are usually 300-600 diodes per inch.
A circuit board converts the electricity to numbers and send the information to the computers
Color Scanners
use filters to separate the components of color into the primary additive colors (red, green, and blue) at each point
Red, Green, and Blue (RGB) are primary additive colors because they can be combined to create any other color
The image scanner is useful because it translates printed images into an electronic format that can be stored in a computer’s memory
Optical Character Recognition (OCR)
Converts scanned image into editable text
Image is stored in the computer’s memory as a bitmap.
Bitmap is a grid of dots, each dot represented by one or more bits
translate that array of dots into text that the computer can interpret as letters and numbers
Each letter is scanned
Letters are compared to known letters
Best match is entered into document
Rarely 100% accurate
Scanner types
Handheld scanners
- more portable but typically require multiple passes to scan a single page
Flatbed scanners
- offer higher-quality reproduction than do handheld scanners and
- can scan a page in a single pass
Audiovisual Input Devices
Microphones
- Used to record speech
- Speech recognition
- “Understands” human speech
- Allows dictation or control of computer
- Matches spoken sound to known phonemes
- Enters best match into document
Speech Recognition
demand for translating spoken words into text
Translating voice to text is a capability known as speech recognition (or voice recognition).
With it, you can dictate to the computer instead of typing, and you can control the computer with simple commands
translates Phonemes into text or commands
Other type of Audio Input
Computers can accept many kinds of audio input
Sound card with the appropriate plugs
- a compact disc
- a tape player
- a radio or
- even a record player
If the audio source outputs sounds in the form of analog, sound card must convert the analog signals into digital code so the computer can store and use it.
Musical Instrument Digital Interface (MIDI)
Connects musical instruments to computer
Digital recording or playback of music
Musicians can produce professional results
Video Input
With growth of multimedia and the Internet, computer users are adding video input capabilities to their systems in great numbers
Applications such as video conferencing enable people to use full-motion video images
Videos are commonly used in presentations and on Web pages
Video Camera and Webcam
video cameras used with computers digitize images by breaking them into individual pixels
pixel is one or more dots that express a portion of an image
Each pixel’s color and other characteristics are stored as digital code
With Webcam the user can “capture” images of himself or herself while working at the computer
Digital Cameras
portable, handheld devices that capture still images
digitizes the image
compresses it, and
stores it on a special memory card.
user can then copy the information to a PC, where the image can be edited, copied, printed, embedded in a document, or transmitted to another user
Digital cameras have become standard equipment for designers of all kinds.
In Web page design,digital cameras enable designers to shoot a subject and quickly load the images onto their computers.
This process saves the step of acquiring existing photographs or developing and printing film-based photos—which must be scanned into the computer.
Designers can update a Web site’s illustrations quickly and regularly using digital cameras.
Graphic designers can edit and enhance digital photographs in innumerable ways, using photo-editing software