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Snippet of code used for DevFest London 2017 to count faces in audience and send to Google Analytics and update image in Google Slides (see https://mashe.hawksey.info/?p=17787)
import io
import picamera
import cv2
import numpy
import requests
import base64
def hitGA(faces):
print("Sending to GA")
requests.get("http://www.google-analytics.com/collect?v=1" \
+ "&tid=YOUR_UA_TRACKING_ID_HERE" \
+ "&cid=1111" \
+ "&t=event" \
+ "&ec=FaceDetection" \
+ "&ea=faces" \
+ "&el=DevFest17"
+ "&ev=" + faces).close
maxFaces = -1
#Setup posting result to Slides
url = 'PUBLISHED_WEB_APP_URL_FROM_GOOGLE_APPS_SCRIPT'
# prepare headers for http request
content_type = 'image/jpeg'
headers = {'content-type': content_type}
while True:
#Create a memory stream so photos doesn't need to be saved in a file
stream = io.BytesIO()
#Here you can also specify other parameters (e.g.:rotate the image)
with picamera.PiCamera() as camera:
camera.resolution = (2592, 1944)
camera.iso = 800
camera.capture(stream, format='jpeg')
#Convert the picture into a numpy array
buff = numpy.fromstring(stream.getvalue(), dtype=numpy.uint8)
#Now creates an OpenCV image
image = cv2.imdecode(buff, 1)
#Load a cascade file for detecting faces
face_cascade = cv2.CascadeClassifier('/usr/share/opencv/haarcascades/haarcascade_frontalface_alt.xml')
#Convert to grayscale
gray = cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
#Look for faces in the image using the loaded cascade file
faces = face_cascade.detectMultiScale(gray, 1.1, 5)
facesInt = len(faces)
print ("Found " + str(facesInt) + " face(s)")
#Send faces counted to GA
hitGA(str(facesInt))
#Draw a rectangle around every found face
for (x,y,w,h) in faces:
cv2.rectangle(image,(x,y),(x+w,y+h),(255,255,0),2)
#Save the result image if new maximum
if facesInt > maxFaces:
retval, buffer = cv2.imencode('.jpg', image)
img_encoded = base64.b64encode(buffer)
response = requests.post(url, data=img_encoded, headers=headers)
maxFaces = facesInt
print (response.text)
#Show the result image
imS = cv2.resize(image, (640, 360))
cv2.imshow('frame', imS)
k = cv2.waitKey(1000)
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