def _determine_pad_amount(image_array, max_height, max_width):
    """
    Given an image and desired max height/width,
    find how much height and width is needed to make
    the image the appropriate size
    """
    height, width, _ = image_array.shape
    height_needed = max_height - height
    width_needed = max_width - width
    return height_needed, width_needed
