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 are designed to alleviate wrist strain -- particularly carpal tunnel syndrome. images courtesy of fentek-ind.com and darwinkeyboards.com

A A A A A A A A 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 A A A A A A A A

F F 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 serifs F Arial, 208 pt., italic Times New Roman, 229 pt., regular

Image File Size: Contributors Original 56K 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 Lower res 51K 8-bit color 35K 50% size 10K

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 1 bit line art 1 bit halftone 8-bit grayscale 24-bit color Pictures appear courtesy of Mustek http://www.mustek.com.tw/Support/html/scannings.html

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 resolution may differ from vertical resolution higher the resolution, the “truer” the image. monitors: 50-100 dpi printers (inkjet): 100-200 dpi printers (laser): 300-1200 dpi George Seurat, Sunday Afternoon on La Grande Jatte from Art.com

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