Adding to the Face Recognition data path new images , and not overwriting them

Question

I'm currently working in a face recognition project using OpenCV and python. The thing is, that the accuracy of the face recognition is not so good, so I'm thinking about adding more images in the data path, with different lighting, backgrounds etc in order to improve it. The problem here is that whenever I use

cv2.imwrite("data/User."+str(face_ID)+"."+str(count)+".jpg", gray[y:y+h, x:x+w])

it overwrites the previous saved images in the path.

I works fine, but I just want to do something like appending the new images to the path, every time I run the function.

Here is the data generator section.

def data_generator():

    count = 0

    # asking user for data input

    face_ID = input("[INFO] Please enter user ID and press <return> ")

    print("[INFO] Thank you\n Now please look at the camera and wait.")
  # start the video capture

    cap = cv2.VideoCapture(0)
    try:

        while True:

            # Here we detect the face

            ret, img = cap.read()
            gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

            # Detecting faces

            faces = detector.detectMultiScale(gray,
                scaleFactor = 1.3,
                minNeighbors = 5,
                minSize= (20, 20)
                )

            for (x, y, w, h) in faces:

                cv2.rectangle(img, (x,y), (x+w, y+h), (0,255,0), 2)

                roi_gray = gray[y:y+h, x:x+w]
                roi_img = img[y:y+h, x:x+w] 


                count += 1

            cv2.imwrite("data/User."+str(face_ID)+"."+str(count)+".jpg", gray[y:y+h, x:x+w])

            cv2.imshow('img', img)

            k = cv2.waitKey(10) & 0xff

            if k == 27:
                break

            elif count >= 30:
                break
    except KeyboardInterrupt:
        pass

    print("[INFO] Data gathered.")

    print("[INFO] Saving Data.")
    print("[INFO] Exiting program and cleanup stuff")

    cap.release()
    cv2.destroyAllWindows()

Answer 1

I think the problem is you have your cv2.imwrite("data/User."+str(face_ID)+"."+str(count)+".jpg", gray[y:y+h, x:x+w]) outside your while True: loop.

I also use os.path.join and .format for saving images. So you can define a directory outside the loop and use .format like this for better overview IMO:

cv2.imwrite(os.path.join(directory, 'User.{}.{}.jpg'.format(face_ID, count)), gray[y:y+h, x:x+w])