Images: We rely on images for information, entertainment, and visual appeals.
Origins of images:
o Non-digital mediums (Paper copy of a photo)
o Photography (Images uploaded to a file on the computer)
o Clip art images (Images created and saved to a file on the computer)
o Binary: A numerical system containing only 0s and 1s
o Octal: A numerical system containing 8 digits
o Decimal: A numerical system containing 10 digits
o Hexadecimal: A numerical system containing 16 digits (including alphabets A – F)
Bit: Fundamental unit of information in a computer system that uses binary. This is because computers are electronic
devices that have only two possible states: on – high voltage or off – low voltage.
Digitization: Process of translating piece of information into binary bits
o The information takes a series of values that equal either ‘0’ or ‘1’
More bits used to encode colors mean more colors available to assign to a picture (y = 2f)bits
1 bit can take on 2 value (colors)
2 bit can take on 4 values (colors)
3 bits can take on 8 values (colors)
o Conversion from analog to digital: A two-step process with:
Sampling: How many pixels will I break up the image into?
Pixel: Smallest image component with 1 color assigned to it
When images are taken from scanners or cameras, they are represented in pixels.
The more samples are taken, the clearer the picture becomes.
Quantizing: How many discrete values will I use to represent each pixel?
Each pixel is given a numerical value that represents the corresponding color
Using 8 bits (1 byte), it is possible to obtain 256 values of colors
Subtractive Model (CMYK)
o Primary colors are cyan, magenta, yellow, and black
o Used for printing (commercial plates and inks)
o Uses printer ink. When applied to paper, removes colors from a white background. Additive model (RGB):
o Primary colors are red, green, an blue
o Adds ‘light’ to a black background (monitor)
o Used for web. This is because cathode ray devices display colors with red green and blue light. RGB can also
represent a large portion of the color spectrum by mixing the three colors on a monitor.
o Brighter than CMYK
o True color: Uses 24 bit color representation (~16 million colors)
o RGB code:
Each pixel is represented by 3 numbers of 2 bits
Total of approximately 16 million colors available.
Each value ranges from 0 (no amount) to 255 (max amount)
Red: <255, 0, 0>
Green: <0, 255, 0>
Blue: <0, 0, 255>