code: def contrast(x, severity=1):
    
    c = [0.4, .3, .2, .1, .05][severity - 1]
  
    x = np.array(x) / 255.
    means = np.mean(x, axis=(0, 1), keepdims=True)
    x_clip = np.clip((x - means) * c + means, 0, 1) * 255
    return around_and_astype(x_clip)
docs: Change contrast of images.
  
    Args:
      x: numpy array, uncorrupted image, assumed to have uint8 pixel in [0,255].
      severity: integer, severity of corruption.
  
    Returns:
      numpy array, image with uint8 pixels in [0,255]. Changed contrast.