1. 10/10: Input & Output Definitions Input devices: examples
Output devices: examples
Keyboards
Scanners: OCR
Fonts
Image File Size: Color Depth, Resolution

2. 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

3. 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

4. Input devices: examples
keyboards · fax modems
pointing devices · scanners
microphones
images courtesy of logitech.com, keytronic.com, buy.com,

5. Output devices: examples
monitors · printers
speakers · feedback game controllers
Images courtesy of viewsonic.com, yamaha.com, logitech.com

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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 = ?

13. Resolution resolution: dpi dots per linear inch
horizontal resolution may differ from vertical resolution
higher the resolution, the “truer” the image.
monitors: dpi printers (inkjet): dpi printers (laser): dpi
George Seurat, Sunday Afternoon on La Grande Jatte from Art.com

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