How to store images with bounding box in a folder using python google colab?

I am trying to save the images after detecting faces in them. I tried using matplotlib.pyplot.savefig(img, bbox_inches='tight', pad_inches=0) and this stored images but all the images stored are blank white images. The output I get

what I want it to store is:- The Output I expect

#face detection with mtcnn on a photograph
from matplotlib import pyplot
from mtcnn.mtcnn import MTCNN
from matplotlib.patches import Rectangle
from matplotlib.patches import Circle
import glob
import cv2
import matplotlib
# draw an image with detected objects
def draw_image_with_boxes(filename, result_list):
    # load the image
    data = pyplot.imread(filename)
    # plot the image
    pyplot.imshow(data)
    # get the context for drawing boxes
    ax = pyplot.gca()
    # plot each box
    for result in result_list:
        # get coordinates
        x, y, width, height = result['box']
        # create the shape
        rect = Rectangle((x, y), width, height, fill=False, color='red')
        # draw the box
        ax.add_patch(rect)
        # draw the dots on eyes nose ..
        #for key, value in result['keypoints'].items():
            # create and draw dot
            #dot = Circle(value, radius=2, color='red')
            #ax.add_patch(dot)
    # show the plot
    pyplot.show()
    
#filename = '/content/drive/My Drive/images/*.jpg'
i = 1
for filename in glob.glob('/content/drive/My Drive/images/*.jpg'):
   pixels = cv2.imread(filename)

   # load image from file
   #pixels = pyplot.imread(filename)
   # create the detector, using default weights
   detector = MTCNN()
   # detect faces in the image
   faces = detector.detect_faces(pixels)
   # display faces on the original image
   new = draw_image_with_boxes(filename, faces)
   img = '/content/drive/My Drive/boundingBox' + '/image_' + str(i) + '.jpg'
   
   matplotlib.pyplot.savefig(img, bbox_inches='tight', pad_inches=0)
   
   i+=1
print("Done")