Canny Edge Detection

canny and gradient

grad text

Note! The standard location of the origin (x=0, y=0) for images is in the top left corner with y values increasing downward and x increasing to the right. This might seem weird at first, but if you think about an image as a matrix, it makes sense that the "00" element is in the upper left.

Now let's try a quiz. Below, I’m plotting a cross section through this image. Where are the areas in the image that are most likely to be identified as edges?

canny intro quiz

Edges quiz

The red line in the plot above shows where I took a cross section through the image. The wiggles in the blue line indicate changes in intensity along that cross section through the image. Check all the boxes of the letters along this cross section, where you expect to find strong edges.

A

B

C

D

E

F

SOLUTION:

A
C
E