opencv - How to crop an image into polygon shape in python -

i'm trying make gui helps me cropping faces , foldering them according moods such angry, sad, happy, etc. code looks working fine when crop image saves rest of image. don't know how can accomplish that!! cropping fuctions:

    def on_mouse(self, event, x, y, buttons, user_param):     # mouse callback gets called every mouse event (i.e. moving, clicking, etc.)      if self.done: # nothing more         return      if event == cv2.event_mousemove:         # want able draw line-in-progress, update current mouse position         self.current = (x, y)     elif event == cv2.event_lbuttondown:         # left click means adding point @ current position list of points         print("adding point #%d position(%d,%d)" % (len(self.points), x, y))         self.points.append((x, y))     elif event == cv2.event_rbuttondown:         # right click means we're done         print("completing polygon %d points." % len(self.points))         self.done = true   def run(self, image):     # let's create our working window , set mouse callback handle events     cv2.namedwindow(self.window_name, flags=cv2.window_autosize)     cv2.imshow(self.window_name, image)     cv2.waitkey(1)     cv2.setmousecallback(self.window_name, self.on_mouse)      while(not self.done):         # our drawing loop, continuously draw new images         # , show them in named window         if (len(self.points) > 0):             # draw current polygon segments             cv2.polylines(image, np.array([self.points]), false, final_line_color, 1)             # ,  show current segment             cv2.line(image, self.points[-1], self.current, working_line_color)         # update window         cv2.imshow(self.window_name, image)         # , wait 50ms before next iteration (this pump window messages meanwhile)         if cv2.waitkey(50) == 27: # esc hit             self.done = true      # user finised entering polygon points, let's make final drawing     # of filled polygon     if (len(self.points) > 0):         cv2.fillpoly(image, np.array([self.points]), final_line_color)     # , show     cv2.imshow(self.window_name, image)     # waiting user press key     cv2.waitkey()      cv2.destroywindow(self.window_name)     return image 

i added whole code here if need

edit : when changed lines in open function:

filename = unicode(filename.toutf8(), encoding="utf-8") img = cv2.imread(filename) 

to this:

im = image.open(filename).convert("rgba") imarray = numpy.asarray(im) real_image = imageviewer.run(imarray) 

it gaves me errors: connected pydev debugger (build 162.1967.10) corrupt jpeg data: premature end of data segment traceback (most recent call last): file "c:/users/asus/desktop/cgg/gui/template2.py", line 156, in open im = image.open(filename).convert("rgba") file "c:\python27\lib\site-packages\pil\image.py", line 1956, in open prefix = fp.read(16) attributeerror: 'qstring' object has no attribute 'read'

i file name code lines way

filename = qtgui.qfiledialog.getopenfilename(self, "open file",             qtcore.qdir.currentpath()) if filename:    image = qtgui.qimage(filename)    if image.isnull():       qtgui.qmessagebox.information(self, "image viewer",                     "cannot load %s." % filename)             return