Feature Extraction

Question 1

Shape features

Answer 1

Are only dependent on binary mask. Describes the shape of object, can be region or boundary features

Question 2

Boundary features

Answer 2

Chain code
Concavity trees
Convex hulls
Signatures

Question 3

Region features

Answer 3

Includes topological features.

Area
P2A
Euler
Texture
Perimeter

Question 4

Shape feature: Area

Answer 4

Number of pixels

Question 5

Shape feature: P2A

Answer 5

Compactness, perimeter squared divided by area

Question 6

Shape feature: Euler number

Answer 6

Topological descriptor. Number of objects divided by the total number of holes in objects

Question 7

Shape feature: Texture

Answer 7

Smoothness or regularity of region. Can be computed as statistical, structural or spectral property.

Question 8

Shape feature: Perimeter

Answer 8

Simplest number of pixels on boundary.

Question 9

Shape feature: Chain code

Answer 9

Describes boundary. Four or eight step, goes around object edge.

Question 10

Shape feature: Skeletons

Answer 10

Describes middle skeleton of object. Can be found by thinning object or by MAT.

Question 11

Topological descriptors

Answer 11

Connected components
Number of holes
Euler number

Question 12

Shape feature: Signature

Answer 12

1D representation of boundary. Distance from centre point to the border as function of angle.