Lucas-Kanade Window Sum

Problem

Accumulate the sums that build the Lucas-Kanade structure matrix over one window.

Return [sum(ix^2), sum(ix*iy), sum(iy^2)] over the two H x W gradient maps, each rounded to 4 decimal places. An all-zero window returns zeros.

Hint

These three sums form the symmetric 2x2 matrix inverted by Lucas-Kanade.

case 1

in: [[[1,2],[3,4]],[[1,1],[1,1]]]

expected: [30,10,4]

case 2

in: [[[1,0],[-1,0]],[[0,1],[0,-1]]]

expected: [2,0,2]

case 3

in: [[[2]],[[3]]]

expected: [4,6,9]

case 4

in: [[[0,0],[0,0]],[[0,0],[0,0]]]

expected: [0,0,0]

Starter codePython

def lk_window_sum(ix, iy):
    # Your code here
    pass

4 test cases · run your code against them in the editor