[Image-SIG] Second Derivative Test
Ahmad Affzan Abdullah
triple_ace at hotmail.com
Mon Jun 12 13:24:29 CEST 2006
Hi
I'm trying to do a second derivative test to an image for the purpose of
finding extrema. I just want to make sure whether these are true or not:
Dxx = D(x+1,y) + D(x-1,y) - 2D(x,y)
Dyy = D(x,y+1) + D(x,y-1) - 2D(x,y)
Dxy = D(x+1,y+1) + D(x+1,y-1) + D(x-1,y-1) + D(x-1,y+1) - 4D(x,y)
Secondly, I'm trying to store all the extrema detected in a Nx2 array where
N is the number of extrema, and 2 being the x and y coordinates of them.
Since I don't know how many extrema will be detected, can we create an empty
array in python without specifying the size, and later append the data to
that array
Thanks a lot
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