CS 101 – Nov. 16 2 more major topics left: Image enhancement Communication Encryption Networking HTML

Enhancing an image Input = original image (x) Output = final image (y)

Brighten To brighten, we increase pixel values. Simple function like y = x + 20 won’t work Real filter functions have complex formulas Better to “draw” the filter function

Filter function Axes for input and output pixel values 255 255 255 255

Brighten We want output > input. 255 255 brighter darker 255 255

Darken We want output < input. 255 255 brighter darker 255 255

Increase contrast What do we want? 255 255 brighter darker 255 255

Increase contrast Bright get brighter; dark get darker 255 255 255 128 255

Decrease contrast? What should this look like? 255 255 brighter darker 255 128 255

Decrease contrast “Robin Hood” 255 255 brighter darker 255 128 255