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
+10
----------111
Copyright © 2009 by Helene G. Kershner
1100 . 10
+ 10 . 10
--------------1111 . 10
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.
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters



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 © 2009 by Helene G. Kershner
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.
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters
 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 © 2009 by Helene G. Kershner
Bits are Not just for Characters

Images:
 Black

and white TV, and early computer monitors
used lighted pixels of a single color to produce
Characters
images.
 Early computer monitors were not necessarily black
and white.
Today the “world” is in color.
 Well sort of…..
Copyright © 2009 by Helene G. Kershner
Bits are Not just for 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
Copyright © 2009 by Helene G. Kershner
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
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- 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 © 2009 by Helene G. Kershner
Bits are Not just for Characters -- 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.
Copyright © 2009 by Helene G. Kershner
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
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- Images
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- Images
grayscale
true color
http://en.wikipedia.org/wiki/Bits_per_pixel
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- Images
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
Copyright © 2009 by Helene G. Kershner
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
Copyright © 2009 by Helene G. Kershner
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
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- 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
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- 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
Copyright © 2009 by Helene G. Kershner
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
Copyright © 2009 by Helene G. Kershner
Bits are Not just for Characters -- 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 © 2009 by Helene G. Kershner