Gradient Direction Angle

Problem

Compute the Sobel gradient direction angle at every valid pixel.

For each 3x3 window compute sx and sy with the Sobel kernels, then angle = degrees(atan2(sy, sx)) mod 180, rounded to 2 decimal places. Return the (H - 2) x (W - 2) map.

Hint

Use atan2(sy, sx) so the quadrant is handled automatically, then reduce mod 180.

Test cases

case 1

in: [[[7,7,7],[7,7,7],[7,7,7]]]

expected: [[0]]

case 2

in: [[[0,0,0],[0,0,0],[0,0,10]]]

expected: [[135]]

case 3

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

expected: [[90]]

case 4

in: [[[1,2,3],[4,5,6],[7,8,9]]]

expected: [[108.43]]

Starter codePython

def gradient_direction(image):
    # Your code here
    pass

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