'Combines an rgb image with an intensity map using "soft light"
blending.  Uses the "pegtop" formula.
Parameters
rgb : ndarray
An MxNx3 RGB array of floats ranging from 0 to 1 (color image).
intensity : ndarray
An MxNx1 array of floats ranging from 0 to 1 (grayscale image).
Returns
rgb : ndarray
An MxNx3 RGB array representing the combined images.'

def blend_soft_light(self, rgb, intensity):

    return (((2 * intensity) * rgb) + ((1 - (2 * intensity)) * (rgb ** 2)))
