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10/10: Input & Output • Definitions • Input devices: examples • Output devices: examples • Keyboards • Scanners: OCR • Fonts • Image File Size: Color Depth, Resolution

10/10: Input & Output Definitions Input devices: examples Output devices: examples Keyboards Scanners: OCR Fonts Image File Size: Color Depth, Resolution

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10/10: Input & Output

• Definitions

• Input devices: examples

• Output devices: examples

• Keyboards

• Scanners: OCR

• Fonts

• Image File Size: Color Depth,Resolution

Definitions

• Input: “to enter data into the computer for processing; the data entered.”

• Output: “to transfer data from the computer to devices that allow you to see, hear, or feel it; the data transferred.”

images courtesy of keytronic.com, viewsonic.com

What is the essential qualification?

• For something to be qualified as an input or output device, it must be an interface between the user and the computer.

• Cables, dial-up modems, etc. would NOT be input or output devices.

images courtesy of logitech.com, viewsonic.com

Input devices: examples

• keyboards fax modems

• pointing devices scanners

• microphones

images courtesy of logitech.com, keytronic.com, buy.com,

Output devices: examples

• monitors printers

• speakers feedback game controllers

Images courtesy of viewsonic.com, yamaha.com, logitech.com

The Keys on the Keyboard

• for inputting text

• Standard keyboard– alphanumeric keys – function keys (F1)– shift keys (left shift)– toggle keys (caps lock)– special function keys (enter, windows, menu, home,

end, page up/down, delete, backspace, esc)

You will be expected to know what the keys on the keyboard do.

Image courtesy of fentek-ind.com

Ergonomic Keyboards

• Ergonomics: how machines and humans interact, with an emphasis on bodily stress and fatigue.

• Ergonomic keyboards aredesigned to alleviate wriststrain -- particularly carpaltunnel syndrome.

images courtesy of fentek-ind.com and darwinkeyboards.com

Scanners: OCR

• Optical Character Recognition

• We see characters, and recognize them as letters

• Paper copy becomes– Scanned image becomes– Bitmapped image (bitmap)– Via feature extraction

process becomes– Text file

AA

A

AA

AAA

Fonts• Types of fonts: typeface family: Arial, Times

Roman

• serifs: things on end of letters

• Types of fonts: style: regular, bold, italic, shadow

• size: measured in points (72 pts/in)

F Fserifs

Arial, 208 pt., italic

Times New Roman, 229 pt., regular

Image File Size: Contributors• Images are stored on a per-bit

basis:– Bigger the physical image =

bigger the file size– Deeper the color depth = bigger

the file size– Higher the resolution = bigger

the file size 8-bit color 35K

50% size 10K

Lower res 51K

Original 56K

Color Depth

• Color depth is the number of bits that are stored for each pixel

• 1-bit B&W– line art– halftone

• 8-bit grayscale

• 24-bit color

Pictures appear courtesy of Mustek http://www.mustek.com.tw/Support/html/scannings.html

1 bit line art 1 bit halftone

8-bit grayscale 24-bit color

Why 24-bit Color?

• Color is stored as the combination of three colors: red, green, & blue (RGB).

• Each color has a value stored for it using 8 bits.

• 3 colors x 8 bits = 24 bits total.

• How many levels for each color can be recorded?– 8 bits per color = 2 to the 8th power = ?

Resolution

• resolution: dpi dots per linear inch

• horizontal resolutionmay differ from vertical resolution

• higher the resolution, the “truer” the image.

• monitors: 50-100 dpiprinters (inkjet): 100-200 dpiprinters (laser): 300-1200 dpi

George Seurat, Sunday Afternoon on La Grande Jatte from Art.com

300 dpi: no zoom, 400% zoom 150 dpi: no zoom, 400% zoom

Resolution