I'm using the code below (which is a googling result) to detect faces:
import io import picamera import cv2 import numpy import PIL from PIL import Image from resizeimage import resizeimage #Load a cascade file for detecting faces face_cascade = cv2.CascadeClassifier('/usr/share/opencv/haarcascades/haarcascade_frontalface_alt.xml') #Create a memory stream so photos doesn't need to be saved in a file stream = io.BytesIO() #Get the picture (low resolution, so it should be quite fast) #Here you can also specify other parameters (e.g.:rotate the image) with picamera.PiCamera() as camera: camera.resolution = (640, 480) camera.vflip = False camera.hflip = False camera.brightness = 60 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) print "Found "+str(len(faces))+" face(s)" #Draw a rectangle around every found face #Crop faces and save to separate files id = 1 for (x,y,w,h) in faces: cv2.rectangle(image,(x,y),(x+w,y+h),(255,0,0),2) cropped = image[ y : y+h, x : x+w ] #RESIZE IMAGE to 92x112 cropped = cv2.resize(cropped,None,92,112) cv2.imwrite("../reco/test_faces/cropped_face" + str(id) + ".png", cropped) id = id + 1 At the end I want to crop the faces into image files and resize them to 92x112. This is what I try with:
cropped = cv2.resize(cropped,None,92,112) When I run this I get:
OpenCV Error: Assertion failed (dsize.area() || (inv_scale_x > 0 && inv_scale_y > 0)) in resize, file /build/opencv-ISmtkH/opencv-2.4.9.1+dfsg/modules/imgproc/src/imgwarp.cpp, line 1835 Traceback (most recent call last): File "1track.py", line 48, in <module> cropped = cv2.resize(cropped,None,92,112) cv2.error: /build/opencv-ISmtkH/opencv-2.4.9.1+dfsg/modules/imgproc/src/imgwarp.cpp:1835: error: (-215) dsize.area() || (inv_scale_x > 0 && inv_scale_y > 0) in function resize 
