- group pixels w a segmentation algorithm
- can group pixels by optical flow - “pixels that move together are part of the same entity”
Unsupervised segmentation: how can pixels in an image be grouped w/o prior labels?
Use cases
- object identification
- efficiency (processing groups rather than individual pixels)
- foreground-background separation
Examples
Challenges:
- noise
- blur
- color variation
What is a good segment?
- proximity (nearby pixels belong together)
- similarity (color, shape)
- common fate (moving together)
- symmetry & continuity (aligned edges )
But it is subjective and context-dependent.
- gesalt theory: whole is greater than sum of its parts - relationships btw parts can yield new properties
- grouping is key to visual perception
next: clustering