Standardization of Image Pixels

Problem

Standardize an image to zero mean and unit variance.

Compute the population mean and standard deviation over all pixels, then return (v - mean) / std rounded to 4 decimal places. If the standard deviation is 0, return a same-shaped grid of zeros.

Test cases

case 1

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

expected: [[-1.3416,-0.4472],[0.4472,1.3416]]

case 2

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

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

case 3

in: [[[10]]]

expected: [[0]]

case 4

in: [[[2,4,4,4],[5,5,7,9]]]

expected: [[-1.5,-0.5,-0.5,-0.5],[0,0,1,2]]

Starter codePython

def standardize(image):
    # Your code here
    pass

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