Python+OpenCV: cv2.imwrite

Question

I'm trying to detect a face and write down area with the face in a separate file. How can I do it? I think that i must use "faces" (you can see this var in code). But how?

from ffnet import mlgraph, ffnet, tmlgraph, imlgraph import pylab import sys import cv,cv2 import numpy cascade = cv.Load('C:\opencv\data\haarcascades\haarcascade_frontalface_alt.xml')   def detect(image):  bitmap = cv.fromarray(image)  faces = cv.HaarDetectObjects(bitmap, cascade, cv.CreateMemStorage(0))  if faces:   for (x,y,w,h),n in faces:      cv2.rectangle(image,(x,y),(x+w,y+h),(255,255,255),3)  return image  if __name__ == "__main__":     cam = cv2.VideoCapture(0)     while 1:         _,frame =cam.read()         frame = numpy.asarray(detect(frame))         cv2.imshow("features", frame)         if cv2.waitKey(1) == 0x1b: # ESC             print 'ESC pressed. Exiting ...'             break 

Answer 1

This following code should extract face in images and save faces on disk

def detect(image):     image_faces = []     bitmap = cv.fromarray(image)     faces = cv.HaarDetectObjects(bitmap, cascade, cv.CreateMemStorage(0))     if faces:         for (x,y,w,h),n in faces:             image_faces.append(image[y:(y+h), x:(x+w)])             #cv2.rectangle(image,(x,y),(x+w,y+h),(255,255,255),3)     return image_faces  if __name__ == "__main__":     cam = cv2.VideoCapture(0)     while 1:         _,frame =cam.read()         image_faces = []         image_faces = detect(frame)         for i, face in enumerate(image_faces):             cv2.imwrite("face-" + str(i) + ".jpg", face)          #cv2.imshow("features", frame)         if cv2.waitKey(1) == 0x1b: # ESC             print 'ESC pressed. Exiting ...'             break 

Answer 2

Alternatively, with MTCNN and OpenCV(other dependencies including TensorFlow also required), you can:

1 Perform face detection(Input an image, output all boxes of detected faces):

from mtcnn.mtcnn import MTCNN import cv2  face_detector = MTCNN()  img = cv2.imread("Anthony_Hopkins_0001.jpg") detect_boxes = face_detector.detect_faces(img) print(detect_boxes) 

[{'box': [73, 69, 98, 123], 'confidence': 0.9996458292007446, 'keypoints': {'left_eye': (102, 116), 'right_eye': (150, 114), 'nose': (129, 142), 'mouth_left': (112, 168), 'mouth_right': (146, 167)}}]

2 save all detected faces to separate files:

for i in range(len(detect_boxes)):     box = detect_boxes[i]["box"]     face_img = img[box[1]:(box[1] + box[3]), box[0]:(box[0] + box[2])]     cv2.imwrite("face-{:03d}.jpg".format(i+1), face_img) 

3 or Draw rectangles of all detected faces:

for box in detect_boxes:     box = box["box"]     pt1 = (box[0], box[1]) # top left     pt2 = (box[0] + box[2], box[1] + box[3]) # bottom right     cv2.rectangle(img, pt1, pt2, (0,255,0), 2) cv2.imwrite("detected-boxes.jpg", img)