bits are not just for numbers or characters computers store characters as bits or binary digits....

Bits are Not just for Numbers or Characters

Computers store characters as bits or binary digits. Characters from the English-language keyboard can be

represented in ASCII as a series of 7-bits. This includes letters, numbers and “special” characters.

Unicode the common coding system because it expands the possible character set. All Internet operations use Unicode.

Computers perform arithmetic in binary (base 2) rather than decimal (base 10). 101 1100 . 10 +10 + 10 . 10

----------- --------------- 111 1111 . 10

Copyright © 2009 by Helene G. Kershner

Bits are Not just for Characters

The World of computers is filled with more than characters and binary numbers.

What else is it filled with? Color Pictures Sound.



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 ….


Bits are Not just for Characters 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.



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.



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…..

Characters



The human eye see images and colors based on the sensitivity of cells in the retina of the eye to different wavelengths of light.

“The retina contains three types of color receptors cells or cones. The brain interprets the information transmitted by the eye into images.

If you are “color blind” some part of the message between the eye and the brain doesn’t work properly. This can be caused by eye or brain dysfunction. It is often related to a lack of certain cone chemicals in the eye.

Human vision (color or black & white) is based on the wavelengths of light reflected off objects.

In the physical world, color is ANALOG.

http://en.wikipedia.org/wiki/Color


Bits are Not just for Characters -- 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



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



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.


Bits are Not just for Characters -- Images 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 (28) different colors. 2

1 A definition from Whatis.com

2. http://www.webopedia.com/TERM/P/pixel.html



grayscale

true color

http://en.wikipedia.org/wiki/Bits_per_pixel



Here the pixels are visible to the eye http://www.youtube.com/watch?v=m0S0qg4Zh7Y

Here the pixels are essentially invisible http://www.youtube.com/watch?v=avMW_hKtcDM


Bits are Not just for Characters -- Sound What is sound?

“Sound is vibration transmitted through a solid, liquid or gas.”

“Sound in humans is those vibrations capable of being detected by the ear” and interpreted by the brain. 1

Sound is a wave Sound waves move through the air Sound waves move through other materials

Sound in animals is physiologically the same, it is heard by the ear and interpreted by the brain but, most animals hear a larger range of sound waves than human.

http://en.wikipedia.org/wiki/Sound


Bits are Not just for Characters -- Sound

Sound is vibration, Sound is a wave Sound is Analog

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

A dog whistle that humans cannot hear. The whistle is still vibrating.

If a tree falls in the forest and no one is there to see it fall, does it make a sound? http://en.wikipedia.org/wiki/Sound



Sound is vibration, Sound is a wave Sound is Analog

http://www.youtube.com/watch?v=VEiEBEadZFI&feature=PlayList&p=448A499C6D44B935&index=6

http://www.youtube.com/watch?v=q19p1df2tWE&feature=related



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


Bits are Not just for Characters -- 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



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


bits are not just for numbers or characters computers store characters as bits or binary digits....

Documents