Technology-Chapter 8 Flashcards
Pixels
from picture elements, are small points of colored light arranged in a grid to form a computer display
RGB-always in that order
Each pixel is formed from three colors lights: red, green, blue
white and black result from,,,
white- high intensity
black-turning off all of them
Intensities
All colors are made by using different amounts of intensities by all three lights.
Pixels , the light shines directly at our eyes which means
nothing is absorbed nor reflected
Thin Film TransiStor (TFT)
A form of liquid crystal display (LCD), known also as active matrix, these are the standard “flat” or “thin” displays used for laptops, phones, and so on.
Representing the color os a single pixels requires..
3 bytes
Brightness refers to
how close to the white the pixels are
Contrast
is the side of the difference between the darkest and lightest portions of the image
100%
white point
0%
black point
gamma point
midpoint
The force , or intensity of the push, determines the volume, and the frequency ( the number of waves per second) of the pushes is the ..
pitch
analog
the key from a digitization point of view is that the object vibrates continuously, producing a continuously changing wave.
convert data to bits
Thomas edison
analog rep.
scratch on a wax cylinder
Sample
to take measurements at regular intervals
sampling rate
the number of samples in a second
Nyquist rule
a sampling rate must be at least twice as fast as the fastest frequency
humans can hear
20,000 hz
transduscer
converts a sound wave into an electrical wave
analog-to-digtal converter (ADC)
digitizing process
an electrical signal is fed into this, which takes the continuos wave and smokes it at regular intervals, outputting for each sample binary numbers
Digital-to-analog converter (DAC)
reversed to play sound
The numbers are read from memory into the decompressor which produces binary numbers, they are inputed into this and creates an electrical wave by interpolation between the digital values- that is, filling in or smoothly moving from one value to another.
Bits must represent
positive and negative values
the more bits, the more accurate the measurements
audio number of bits
16
advantages of digital sound
fix and compress it, reproduce exactly
compression ratio
number of bits is reduced to about one-tenth of what it was
Compression
means to change the representation in order to use fewer bits to store or transmit information
Run-length encoding
uses binary numbers to specify how long the first sequence of 0’s is , then how long the following sequence of 1’s is, then how long the following sequence of 0’s is , and so on.
Run-length encoding is a lossless compression scheme which means
meaning that the original representation of 0’sand 1’s can be perfectly reconstructed from the compressed version.
ex: MP3
lossy compression
that the original representation cannot be exactly reconstructed from the compressed form.
JPEG
invented by the Joint Photographic Experts Group of the ISO. is a lossy compression technique that exploits the same kinds of “human perception” characteristics that MP3 does, only for light and color.
luminance
small changes in brightness
chrominance
small differences in color
MPEG
Motion Picture Experts Group of the ISO, JPEG-type compression is applied to each frame, but then “interframe coherency” is used.
Optical Character Recognition
let you search for a word in the picture, pixel must be converted to text by this process
features
When a computer scans a group of pixels looking for edges where the color changes, form these into this, parts of a character to be recognized
Classifier
uses the features and matches them to an alphabet to determine which one is close
Latency
the time it takes for information to be created or delivered-greatly influences our experience with technology
absolute limit
the speed of light, lenders the fastness of seeing an image
Bandwidth
a measure of how much information is transmitted per unit of time
Bias-Free Universal Medium Principle
bits can represent all discrete information; bits have no inherent meaning
Interpretation
the meaning of bits comes from us or by the computer through our programs
