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10/10: Input & Output Definitions Input devices: examples

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Presentation on theme: "10/10: Input & Output Definitions Input devices: examples"— Presentation transcript:

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,

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,

4 Input devices: examples
keyboards · fax modems pointing devices · scanners microphones images courtesy of,,,

5 Output devices: examples
monitors · printers speakers · feedback game controllers Images courtesy of,,

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

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 and

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

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

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