7. https://emadehsan.com/p/object-detection

py-js-comms.py

import IPython
import time
import sys
import numpy as np
import cv2
import base64
import logging

from google.colab import output
from PIL import Image
from io import BytesIO

def data_uri_to_img(uri):
    """convert base64 image to numpy array"""
    try:
        image = base64.b64decode(uri.split(',')[1], validate=True)
        # make the binary image, a PIL image
        image = Image.open(BytesIO(image))
        # convert to numpy array
        image = np.array(image, dtype=np.uint8); 
        return image
    except Exception as e:
        logging.exception(e);print('\n')
        return None

def run_algo(imgB64):
    """
    in Colab, run_algo function gets invoked by the JavaScript, 
    that sends N images every second, one at a time.
    params:
        image: image
    """
    image = data_uri_to_img(imgB64)  
    if image is None:
        print("At run_algo(): image is None.")
        return

    try:
        # Run detection
        results = model.detect([image], verbose=1)
        # Visualize results
        r = results[0]    
        visualize.display_instances(
            image, 
            r['rois'], 
            r['masks'], 
            r['class_ids'], 
            class_names, 
            r['scores']
            )
    except Exception as e:
        logging.exception(e)
        print('\n')