Keypoint Local Max

Problem

Keep only strict local maxima of a response map.

A pixel is kept with its value rounded to 4 decimals when it is strictly greater than all 8 neighbors and strictly greater than threshold; border pixels are always 0.

Hint

Strict comparisons reject plateaus, so equal neighbors kill the keypoint.

Test cases

case 1

in: [[[0,0,0],[0,9,0],[0,0,0]],5]

expected: [[0,0,0],[0,9,0],[0,0,0]]

case 2

in: [[[1,2,1],[2,9,2],[1,2,1]],5]

expected: [[0,0,0],[0,9,0],[0,0,0]]

case 3

in: [[[0,0,0],[0,9,9],[0,9,9]],5]

expected: [[0,0,0],[0,0,0],[0,0,0]]

case 4

in: [[[0,0,0],[0,4,0],[0,0,0]],5]

expected: [[0,0,0],[0,0,0],[0,0,0]]

Starter codePython

def keypoint_local_max(response, threshold):
    # Your code here
    pass

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