Bits are Not just for Numbers or Characters

Bits are Not just for Numbers or Characters n n 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 n n The World of computers is filled with more than characters and binary numbers. What else is it filled with? n Color n Pictures n Sound. Copyright © 2009 by Helene G. Kershner

Bits are Not just for Characters n n n 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 n 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. n 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. n Copyright © 2009 by Helene G. Kershner

Bits are Not just for Characters n Images: ¨ Black n and white TV, and early computer monitors used lighted pixels of a single color to produce images. Characters ¨ 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 n n n 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 n 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 n 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 n 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 n 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 n http: //www. youtube. com/watch? v=m 0 S 0 qg 4 Zh 7 Y Here the pixels are essentially invisible n http: //www. youtube. com/watch? v=av. MW_h. Ktc. DM Copyright © 2009 by Helene G. Kershner

Bits are Not just for Characters -- Sound n 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 ¨ n ¨ 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 is vibration, Sound is a wave n Sound is Analog n 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. ¨ n 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 is vibration, Sound is a wave n Sound is Analog n http: //www. youtube. com/watch? v=VEi. EBEad. ZFI&feature =Play. List&p=448 A 499 C 6 D 44 B 935&index=6 http: //www. youtube. com/watch? v=q 19 p 1 df 2 t. WE&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/06 aug/02101/physics_soundwaves. htm

Bits are Not just for Characters -- Sound n 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) n n 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