square_black
============


.. image:: /_static/generated_stimuli/papers.white1981.square_black.png
   :alt: square_black stimulus example
   :align: center
   :width: 400px






.. py:function:: stimupy.papers.white1981.square_black(ppd=PPD)


   A square on a black background from White (1981), Fig. 2
   Stimulus size: 4.0 x 4.0 deg (originally 4.3592 deg)
   Target size: 0.72 x 0.72 deg (originally 0.7696 deg)

   :param ppd: Resolution of stimulus in pixels per degree.
   :type ppd: int

   :returns: dict with the stimulus (key: "img") and target mask (key: "target_mask")
             and additional keys containing stimulus parameters
   :rtype: dict of str

   .. rubric:: References

   White, M. (1981).
       The effect of the nature of the surround on the perceived lightness
       of grey bars within square-wave test grating.
       Perception, 10, 215-230.
       https://doi.org/10.1068/p100215