Change brightness 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 brightness.

def brightness(x, severity=1):
  """Change brightness 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 brightness.
  """
  c = [.1, .2, .3, .4, .5][severity - 1]

  x = np.array(x) / 255.
  x = tfds.core.lazy_imports.skimage.color.rgb2hsv(x)
  x[:, :, 2] = np.clip(x[:, :, 2] + c, 0, 1)
  x = tfds.core.lazy_imports.skimage.color.hsv2rgb(x)
  x_clip = np.clip(x, 0, 1) * 255
  return around_and_astype(x_clip)