user interface - how to replace an ongoing process of image capture from another process call over the same ImageLabel in python's GUI TKinter -

i trying use following code create interactive gui changes color-space(hsv, rbg, grayscale etc) on event of button click. display opencv video in tkinter using multiprocessing being new python having problems multiprocessing , attempts on making gui change it's color space on button clicks hangs entire system. on it's implementation highly appreciated. thankyou. below code:

import cv2 pil import image,imagetk import tkinter tk import numpy np multiprocessing import process , queue  def quit_it(root,process):     root.destroy()     process.terminate()  def black_andwhite(root,process):     process.terminate     p=process(target=capture_image, args=(5,queue, ))     p.start()     root.after(0, func=lambda: update_all(root, image_label, queue))  def update_image(image_label, queue):     frame = queue.get()     = image.fromarray(frame)     b = imagetk.photoimage(image=a)     image_label.configure(image=b)     image_label._image_cache = b     root.update()  def update_all(root, image_label, queue):     update_image(image_label, queue)     root.after(0, func=lambda: update_all(root, image_label, queue))  def capture_image(var,queue):     vidfile = cv2.videocapture(0)     while true:        try:           flag, frame=vidfile.read()           if flag==0:              break           if(var==5):              frame1=cv2.cvtcolor(frame, cv2.color_bgr2gray)           else:              frame1=cv2.cvtcolor(frame, cv2.color_bgr2rgb)           queue.put(frame1)           cv2.waitkey(20)        except:           continue   if __name__ == '__main__':     queue=queue();     root=tk.tk()     root.geometry("1500x1200+2+2")     image_label=tk.label(master=root)     image_label.pack()     p=process(target=capture_image, args=(7,queue, ))     p.start()      quit_button=tk.button(master=root, text='quit', command=lambda:quit_it(root,p))     quit_button.pack()      bandw_button=tk.button(master=root, text='black_and_white',command=lambda:black_andwhite(root,p))     bandw_button.pack()      root.after(5, func=lambda: update_all(root, image_label, queue,))     root.mainloop()     p.terminate() 

add logging code see parts executed when. multithreaded code hard debug (because things happen while debugger waits you). logging give report of happened when , allow track down unexpected behavior.$

in case, see 2 problems:

except: continue 

will silently ignore problems in frame capture loop. if goes wrong, no image pushed queue. should cause queue.get() throw empty exception.

the second problem install update_all() twice. have 1 process/loop adds 1 image per n milliseconds queue 2 callbacks in main event loop try image. cause python lock up.

again, use logging see when processes started, when images put queue , taken , how many callbacks registered process images in queue.

[edit] if original code works, use different approach:

instead of installing second callback after() set flag. when flag set, change colorspace. otherwise, leave alone. when button clicked, toggle flag.