1. Bits are Not just for Numbers Computers store characters as bits or binary digits. Characters from the English-language keyboard are represented in ASCII as a series of 7-bits. This includes letters, numbers and “special” characters. Computers perform arithmetic in binary (base 2) rather than decimal (base 10). 101 1100. 10 +10+ 10. 10 -------------------------- 111 1111. 10 Copyright © 2008 by Helene G. Kershner

2. Bits are Not just for Numbers The World of computers is filled with more than characters and binary numbers. What else is it filled with? Color Pictures Sound. Copyright © 2008 by Helene G. Kershner

3. Bits are Not just for Numbers All computer data is represented using bits. Bits can only have two states, on/off, 0/1, black/white, color on/color off. Everything is made up of bits, numbers, letters, symbols, pictures, videos, sound, music …. Copyright © 2008 by Helene G. Kershner

4. Bits are Not just for Numbers Screen images:  Whether we display text or graphics on the screen, all are created as a series of closely placed dots of light.  A pixel, is a dot of light on a computer screen. Pixel is short for picture element.  Resolution is a measure of pixel density on a screen. The more pixels per square inch, the higher the resolution of a screen image, and the clearer and crisper it appears. A traditional monitor displays an image made up of 1024 columns and 786 rows of pixels. This is a pixel density or 1024 x 768 or 786,432 lighted dots. Copyright © 2008 by Helene G. Kershner

5. Bits are Not just for Numbers Images:  Black and white TV, and early computer monitors used lighted pixels of a single color to produce images.  Early computer monitors were not necessarily black and white. Today the “world” is in color.  Well sort of….. Copyright © 2008 by Helene G. Kershner

6. Bits are Not just for Numbers -- Images When displaying graphics, picture and images, a technique called gray-scaling is used. This is much like a “black and white” photograph, where colors are represented not as pure black and white but rather as shades of gray.  Grayscale images vary “from black at the weakest intensity to white at the strongest, though in principle the samples could be displayed as shades of any color” *  Grayscale is NOT black and white, which would be only those colors. * http://en.wikipedia.org/wiki/Grayscale Copyright © 2008 by Helene G. Kershner

7. Bits are Not just for Numbers -- Images Color:  Most color monitors use a red-green-blue (RGB) format.  When these three colors of light are mixed, white light is produced.  A wide range of colors can be obtained by mixing these three colors. * * http://en.wikipedia.org/wiki/RGB_color_model Copyright © 2008 by Helene G. Kershner

8. Bits are Not just for Numbers -- Images Color:  Color requires independent, integrated hardware to light the different- colored pixels in the desired combinations.  Keeping track of and controlling the more complex hardware, requires a color graphics card manage to he pixels.  All of this management requires additional dedicated memory. RGB  The specific color that a pixel describes is some blend of three colors of light (red – green – blue)  Up to three bytes (8-bits each) of data can be used to specifying a pixel's color. 1  One byte for each major color component.  A true color or 24-bit color system uses all three bytes.  Many color monitors use only one byte (8-bits) for each pixel limiting the monitor to only 256 (2 8 ) different colors. 2 1 A definition from Whatis.com 2. http://www.webopedia.com/TERM/P/pixel.html Copyright © 2008 by Helene G. Kershner

9. Bits are Not just for Numbers -- Images Copyright © 2008 by Helene G. Kershner

10. Bits are Not just for Numbers -- Images http://www.lovepixels.pwp.blueyonder.co.uk/ Copyright © 2008 by Helene G. Kershner

11. Bits are Not just for Numbers -- Images grayscale true color http://en.wikipedia.org/wiki/Bits_per_pixel Copyright © 2008 by Helene G. Kershner

12. Bits are Not just for Numbers -- Sound What is sound? Sound is a wave  Sound waves move through the air  Sound waves move through other materials Sound is vibration  The sound of our voice is the vibration made by our vocal chords  A door moving back and forth  The wind  A musical instrument  Vibrating wire  Vibrating reed  Vibrating lips Copyright © 2008 by Helene G. Kershner

13. Bits are Not just for Numbers -- Sound What is a sound wave? It’s a wave of sound. Music is just a bunch of sound waves, arranged in a nice pattern. www.globalsecurity.org/.../ship/acoustics.htm http://library.thinkquest.org/06aug/02101/physics_soundwaves.htm Copyright © 2008 by Helene G. Kershner

14. Bits are Not just for Numbers -- Sound Digital Sound  If sound is a wave, then it is analog, it is something created in the “real” rather than the virtual world of computers.  Sound on a dial telephone was analog, and the sound wave actually travelled over the wires  Digital sound is an approximation of the sound wave using on/off pulses (our bits again) The wave is light gray. The digital equivalent is in red. http://en.wikipedia.org/wiki/Digital_audio Copyright © 2008 by Helene G. Kershner

15. Bits are Not just for Numbers -- Sound  Digital sound is an approximation of the sound wave using on/off pulses (our bits again) Each part of the sound wave is represented by a number of bits The more the wave is broken up into pieces (sample), the more accurate the sound.  CDs use 16-bits/sample  DVD-Audio uses 24-bits/sample http://en.wikipedia.org/wiki/Digital_audio Copyright © 2008 by Helene G. Kershner