10/04 Notes

Image

Image is a matrix

Each cell of a matrix is a pixel

RGB has 3 values in each cell (8 bits each value)

Gray has 1 value in each cell (8 bits for value)

GrayScale

0 = black

255 = white

Also known as pixel intensity

Operations

2 types of transformations
  • photometric - manipulating pixel intensity
  • gemetric - covered later on

Operations List #. Filtering

  • photometric

  • implemeted with convolution

  • depends on filters/masks - also a matrix - tend to be 3 x 3 - can have negative numbers in matrix

    • For GreyScale:
    • multiply value with value it’s over and add them all together - replace center value with value
    • move 1 pixel to right and repeat process for all pixels - pretend modified value is still old value

  • Edge Filters

  1. Gradient Operation
    • A difference in pixels

Edge Filters

S_x == vertical gradient

S_y == horizontal gradient

S_x Matrix:

-1 0 1

-1 0 1

-1 0 1

S_y Matrix:

1 1 1

0 0 0

-1 -1 -1