01:198:170 Chapter Notes - Chapter 8: Digitizing, Auto-Tune, Chrominance
16 May 2018
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Representing Multimedia Digitally
Color Encoding
●Pixels are small points of colored light arranged in a grid
●Each pixel is a combination of 3 colored lights
○Red
○Green
○Blue
●By turning on one light at a time, we can display the 3 colors, turning off all of them makes them
black (absence of light), turning all lights up makes them white (full intensity of each color)
○Black is the absence of light
■Binary: RBG (0000 0000, 0000 0000, 0000 0000)
■Decimal: RBG (0, 0, 0)
■Hex: RBG (0, 0, 0)
○White is the full intensity of each color
■Binary: RBG (1111 1111, 1111 1111, 1111 1111)
■Decimal: RBG (255, 255, 255)
■Hex: (FF, FF, FF)
●All other colors are made by using different amounts, or intensities, of the 3 colors
●We use a byte to denote the intensity of light
○Color of a single pixel requires 3 bytes
○With 24 bits= 2^24=16,777,216 possible colors
●Range of values is 0 to 255 for each color
●Lighten up: Changing colors
○All colors with equal intensities of the RBG subpixels are a shade of gray if they are not
black or white, it’s just a question of whether they’re closer to black or white
Computing on Representations
●When digital info is changed through computation, it is known as computing on representations
:
○Ex: red eye removal
○Photo corrections
○Color changes
○Artistic effects
Brightness and Contrast
●Add in binary
●To make a lighter color of gray, obviously we change the common value to be closer to 255
(maybe by adding 16 to each byte)
●We can add or subtract any amount as long as the result is not less than 0 or greater than 255
○Brightness
■Refers to how close to white pixels are
■Move dial of levels graph to right --> makes all pixels lighter
■Move dial to left --> makes all pixels darker
○Contrast
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Document Summary
Pixels are small points of colored light arranged in a grid. Each pixel is a combination of 3 colored lights. By turning on one light at a time, we can display the 3 colors, turning off all of them makes them black (absence of light), turning all lights up makes them white (full intensity of each color) Binary: rbg (0000 0000, 0000 0000, 0000 0000) White is the full intensity of each color. Binary: rbg (1111 1111, 1111 1111, 1111 1111) All other colors are made by using different amounts, or intensities, of the 3 colors. We use a byte to denote the intensity of light. Color of a single pixel requires 3 bytes. Range of values is 0 to 255 for each color. All colors with equal intensities of the rbg subpixels are a shade of gray if they are not black or white, it"s just a question of whether they"re closer to black or white.
