Extract image patch from bounding box.
copied from
https://github.com/nwojke/deep_sort/blob/master/tools/generate_detections.py
Parameters
----------
image : ndarray
The full image.
bbox : array_like
The bounding box in format (x, y, width, height).
patch_shape : Optional[array_like]
This parameter can be used to enforce a desired patch shape
(height, width). First, the `bbox` is adapted to the aspect ratio
of the patch shape, then it is clipped at the image boundaries.
If None, the shape is computed from :arg:`bbox`.
Returns
-------
ndarray | NoneType
An image patch showing the :arg:`bbox`, optionally reshaped to
:arg:`patch_shape`.
Returns None if the bounding box is empty or fully outside of the image
boundaries.