adapt_normalized_rms_contrast
=============================



.. py:function:: stimupy.utils.adapt_normalized_rms_contrast(img, rms_contrast, mean_luminance=None)


   Adapt normalized rms contrast of image (std divided by mean)

   :param img: stimulus array
   :type img: np.ndarray
   :param rms_contrast: desired rms contrast (std divided by mean intensity)
   :type rms_contrast: float
   :param mean_luminance: desired mean luminance; if None (default), dont change mean luminance
   :type mean_luminance: float

   :returns: **img** -- image with adapted rms contrast and mean luminance if passed
   :rtype: np.ndarray