python - Using OpenCV with Tkinter

Question

I'm writing a program that needs to display a video stream in a Tkinter window. Since there will also be buttons for performing various functions, I'm using grid to organize where everything goes.

The following code, modified from Show webcam sequence TkInter, works fine on my Raspberry Pi:

import Tkinter as tk
import cv2
from PIL import Image, ImageTk

width, height = 800, 600
cap = cv2.VideoCapture(0)

root = tk.Tk()
lmain = tk.Label(root)
lmain.pack()

def show_frame():
    _, frame = cap.read()
    frame = cv2.flip(frame, 1)
    cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
    img = Image.fromarray(cv2image)
    imgtk = ImageTk.PhotoImage(image=img)
    lmain.imgtk = imgtk
    lmain.configure(image=imgtk)
    lmain.after(10, show_frame)

show_frame()
root.mainloop()

However, combining it with Tkinter doesn't work. (In what follows, I've tried commenting out Display 1, Display 2, and neither.)

import numpy as np
import cv2
import Tkinter as tk
import Image, ImageTk

#Set up GUI
window = tk.Tk()  #Makes main window
window.wm_title("Digital Microscope")
window.config(background="#FFFFFF")

#Graphics window
imageFrame = tk.Frame(window, width=600, height=500)
imageFrame.grid(row=0, column=0, padx=10, pady=2)

#Capture video frames
lmain = tk.Label(imageFrame)
cap = cv2.VideoCapture(0)
def show_frame():
    _, frame = cap.read()
    frame = cv2.flip(frame, 1)
    cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
    img = Image.fromarray(cv2image)
    imgtk = ImageTk.PhotoImage(image=img)
    lmain.imgtk = imgtk
    lmain.configure(image=imgtk)
    lmain.after(10, show_frame) 

tk.Label(imageFrame, image=show_frame()).grid(row=0, column=0, padx=10, pady=2)  #Display 1


#Slider window (slider controls stage position)
sliderFrame = tk.Frame(window, width=600, height=100)
sliderFrame.grid(row = 600, column=0, padx=10, pady=2)


show_frame()  #Display 2
window.mainloop()  #Starts GUI

How can I get the video to display in imageFrame?

Answer 1

This should work:

import numpy as np
import cv2
import Tkinter as tk
import Image, ImageTk

#Set up GUI
window = tk.Tk()  #Makes main window
window.wm_title("Digital Microscope")
window.config(background="#FFFFFF")

#Graphics window
imageFrame = tk.Frame(window, width=600, height=500)
imageFrame.grid(row=0, column=0, padx=10, pady=2)

#Capture video frames
lmain = tk.Label(imageFrame)
lmain.grid(row=0, column=0)
cap = cv2.VideoCapture(0)
def show_frame():
    _, frame = cap.read()
    frame = cv2.flip(frame, 1)
    cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
    img = Image.fromarray(cv2image)
    imgtk = ImageTk.PhotoImage(image=img)
    lmain.imgtk = imgtk
    lmain.configure(image=imgtk)
    lmain.after(10, show_frame) 



#Slider window (slider controls stage position)
sliderFrame = tk.Frame(window, width=600, height=100)
sliderFrame.grid(row = 600, column=0, padx=10, pady=2)


show_frame()  #Display 2
window.mainloop()  #Starts GUI

First of all, you have the line tk.Label(imageFrame, image=show_frame()).grid(row=0, column=0, padx=10, pady=2), and since show_frame() doesn't return anything, you've set image to None. Second of all, you need to make sure you lmain.grid(), otherwise lmain won't show.

If you want to have two displays one on top of the other, you could do something like this:

import numpy as np
import cv2
import Tkinter as tk
import Image, ImageTk

#Set up GUI
window = tk.Tk()  #Makes main window
window.wm_title("Digital Microscope")
window.config(background="#FFFFFF")

#Graphics window
imageFrame = tk.Frame(window, width=600, height=500)
imageFrame.grid(row=0, column=0, padx=10, pady=2)

#Capture video frames

cap = cv2.VideoCapture(0)

def show_frame():
    _, frame = cap.read()
    frame = cv2.flip(frame, 1)
    cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
    img = Image.fromarray(cv2image)
    imgtk = ImageTk.PhotoImage(image=img)
    display1.imgtk = imgtk #Shows frame for display 1
    display1.configure(image=imgtk)
    display2.imgtk = imgtk #Shows frame for display 2
    display2.configure(image=imgtk)
    window.after(10, show_frame) 

display1 = tk.Label(imageFrame)
display1.grid(row=1, column=0, padx=10, pady=2)  #Display 1
display2 = tk.Label(imageFrame)
display2.grid(row=0, column=0) #Display 2

#Slider window (slider controls stage position)
sliderFrame = tk.Frame(window, width=600, height=100)
sliderFrame.grid(row = 600, column=0, padx=10, pady=2)

show_frame() #Display
window.mainloop()  #Starts GUI