def draw_box(image, box, color, thickness=2):
    """ Draws a box on an image with a given color.

    # Arguments
        image     : The image to draw on.
        box       : A list of 4 elements (x1, y1, x2, y2).
        color     : The color of the box.
        thickness : The thickness of the lines to draw a box with.
    """
    b = np.array(box).astype(int)
    cv2.rectangle(image, (b[0], b[1]), (b[2], b[3]), color, thickness, cv2.LINE_AA)
 Draws a box on an image with a given color.

    # Arguments
        image     : The image to draw on.
        box       : A list of 4 elements (x1, y1, x2, y2).
        color     : The color of the box.
        thickness : The thickness of the lines to draw a box with.
    
keras_retinanet/utils/visualization.py