Face detection

With the support of Python 3 and OpenCV 3 lots of image processing can be done with ease. In this example we show a simple itom script to detect faces off a webcam live image.

Detection with Webcam

First of all, we need to start the camera with the PLUGIN OpenCVGrabber. The best result for face detection is accomplished with gray images, disregarding the color profile. Using the OpenCV CascadeClassifier function and the MultiScale Detection it returns coordinates of the ROI of the Feature (–> Face) With the Coordinate we simply draw a rectangle onto the image ROI.

We also built a small GUI (Right-click->Save) for seeing a LIVE image of the webcam and a snapshot feature to start calculating the faces.

If you need further assistance, check out the links below.

import cv2
import numpy as np

def detect(img, cascade):
        rects = cascade.detectMultiScale(img, scaleFactor=1.3, minNeighbors=4)
        if len(rects) == 0:
                return []
        rects[:,2:] += rects[:,:2]
        return rects

def draw_rects(img, faces, color):
        for x1, y1, x2, y2 in faces:
                cv2.rectangle(img, (x1, y1), (x2, y2), color, 3)

def autoGrabbing_changed(checked):
        if(checked):
                cam.enableAutoGrabbing()
        else:
                cam.disableAutoGrabbing()

def snap():
        d = dataObject()
        cam.startDevice()
        autoGrabbingStatus = cam.getAutoGrabbing()
        cam.disableAutoGrabbing()
        cam.acquire()
        cam.getVal(d)
        img=np.array(d)
        faces = detect(img, cascade)
        draw_rects(img, faces, (255, 255, 255))
        win.plot["source"] = img
        if(autoGrabbingStatus):
                cam.enableAutoGrabbing()
        cam.stopDevice()

def live():
        win.plot["camera"] = cam

def __del__():
        del cam
        gc()

if __name__ == '__main__':

        win = ui("FaceDetect.ui", ui.TYPEWINDOW, childOfMainWindow = True)
        cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
        nested = cv2.CascadeClassifier('haarcascade_eye.xml')

        try:
                cam= dataIO("OpenCVGrabber",0,'gray')
        except Exception:
                cam = dataIO("DummyGrabber",2048,1024,8)

        #Connect buttons to program
        win.btnSnap.connect("clicked()", snap)
        win.btnLive.connect("clicked()", live)
        win.checkAutoGrabbing.connect("clicked(bool)", autoGrabbing_changed)
        #Initialize gui elements
        win.checkAutoGrabbing["checked"] = cam.getAutoGrabbing()
        #start GUI
        win.show(0)

Result

Facedetection
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