Photoshop soft light blend with Numpy

soft_light_blend.py

import numpy as np
#https://en.wikipedia.org/wiki/Blend_modes#Soft_Light
def soft_light_blend(im1, im2):
    nrm_im1 = im1/255.
    nrm_im2 = im2/255.
    res = np.zeros_like(nrm_im1)

    xif = nrm_im2 < .5
    xel = nrm_im2 >= .5

    a = nrm_im1[xif]
    b = nrm_im2[xif]
    res[xif] = (2 * a * b + (a ** 2) * (1 - 2 * b))

    a = nrm_im1[xel]
    b = nrm_im2[xel]
    res[xel] = (2 * a * (1 - b) + np.sqrt(a) * (2 * b - 1))

    res=res * (255 / res.max())

    return res.astype('uint8')