Week 4

Question 1

what are three types of gradient operators for edge detection

And why is edge detection good?

Answer 1

sobel
prewit
roberts

edge detection will enhance the edges giving a more appealing look

Question 2

what information does the gradient of a pixel tell us

Answer 2

provides info to the strength of the edge

direction of gradient will always be perpendicular to the direction of edge

Question 3

what edges does roberts detects

Answer 3

diagonal edges
1 0 0 -1
0 -1 1 0

Question 4

what edges does prewit date

Answer 4

horizontal and vertical

-1 -1 -1 -1 0 1
0 0 0 -1 0 1
1 1 1 -1 0 1

Question 5

what does sobel detect

Answer 5

horizontal and vertical but with enhancement on the middle

• 1 0 1
• 2 0 2
• 1 0 1

Question 6

what does a laplacian detector find

Answer 6

is an isotropic filter, can detect filter in both x and y axis

0 1 0
1 -4 1
0 1 0