AI on the Edge LESSON 21: Managing Multiple Windows in OpenCV on the Raspberry Pi

Hey everyone, Paul McWhorter here!

Welcome back to the AI on the Edge series!

In today’s lesson, we’re going to take an important next step in computer vision. We’re going to learn how to create, position, resize, and manage multiple windows at the same time using OpenCV on the Raspberry Pi.

This might sound simple, but it’s actually a very big deal. Once you can comfortably work with multiple windows, you can start building much more powerful vision applications — like having a main camera view, a processed view, zoomed-in sections, and debug windows all running at once.

In this lesson we create:

One large main camera window
A smaller color preview
A small grayscale version
Five tiny grayscale windows stacked on the side

This gives you a clean, organized workspace while the camera is running.

What You Learned in This Lesson

How to create multiple named windows with cv2.namedWindow()
How to resize windows using cv2.resizeWindow()
How to precisely position windows on your screen with cv2.moveWindow()
How to work with different resolutions of the same image (full size, half size, quarter size)
Converting between color and grayscale while running live video
Keeping everything running smoothly with good FPS

Mastering multiple windows is one of those foundational skills that separates basic OpenCV projects from more professional and useful vision systems.

Pro Tip: Play around with the window positions and sizes after you get it working. Try making one window much larger, or experiment with different layouts. This is your workspace — make it comfortable!

Ready for the next step? In the next lesson, we’re going to start doing something really cool — we’ll begin combining live video with drawn graphics and start creating interactive vision projects.

Keep building, keep learning, and I’ll see you in the next video!

In the lesson, we develop the code below:

import cv2
import time
from picamera2 import Picamera2
piCam = Picamera2()
W=640
H=360
tStart = time.time()
fps = 0
RES = (W,H)
piCam.preview_configuration.main.size = RES
piCam.preview_configuration.main.format = "RGB888"
piCam.preview_configuration.controls.FrameRate=60
piCam.preview_configuration.align()
piCam.configure("preview")
piCam.start()

textLowerLeft = (int(W*.01),int(H*.05))
fontFace = cv2.FONT_HERSHEY_SIMPLEX
fontThickness = int(W/425)
fontScale = H*.0015
fontColor = (0,0,255)

topBar = 65
windowWaste = 25

cv2.namedWindow("Camera", cv2.WINDOW_GUI_NORMAL)
cv2.resizeWindow("Camera", W, H)
cv2.moveWindow("Camera",0,topBar)

cv2.namedWindow("Camera Small", cv2.WINDOW_GUI_NORMAL)
cv2.resizeWindow("Camera Small",  int(W/2), int(H/2))
cv2.moveWindow("Camera Small",0,topBar+windowWaste+H)
    
cv2.namedWindow("Gray Small", cv2.WINDOW_GUI_NORMAL)
cv2.resizeWindow("Gray Small", int(W/2), int(H/2))
cv2.moveWindow("Gray Small",int(W/2),topBar+windowWaste+H)

grays = ["Gray1","Gray2","Gray3","Gray4","Gray5"]
x = 0
for gray in grays:
    print(gray)
    cv2.namedWindow(gray,cv2.WINDOW_GUI_NORMAL)
    cv2.resizeWindow(gray,int(W/4),int(H/4))
    cv2.moveWindow(gray,W,topBar + x*(int(H/4) + windowWaste))
    x=x+1

while True:
    deltaT = time.time() - tStart
    tStart=time.time()
    fps = fps*.95 + (1/deltaT)*.05
    frame= piCam.capture_array()
    frame=cv2.flip(frame,-1)
    frameSmall=cv2.resize(frame,(int(W/2),int(H/2)))
    frameGraySmall = cv2.cvtColor(frameSmall,cv2.COLOR_BGR2GRAY)

    frameTiny1 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))
    frameTiny2 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))
    frameTiny3= cv2.resize(frameGraySmall,(int(W/4),int(H/4)))
    frameTiny4 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))
    frameTiny5 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))
    

    myText = "FPS: "+str(round(fps,1))
    cv2.putText(frame,myText,textLowerLeft,fontFace,fontScale,fontColor,fontThickness)
    cv2.imshow("Camera", frame)
    cv2.imshow("Camera Small",frameSmall)
    cv2.imshow("Gray Small",frameGraySmall)
    
    cv2.imshow("Gray1",frameTiny1)
    cv2.imshow("Gray2",frameTiny2)
    cv2.imshow("Gray3",frameTiny3)
    cv2.imshow("Gray4",frameTiny4)
    cv2.imshow("Gray5",frameTiny5)


    if cv2.waitKey(1)==ord('q'):
        break
cv2.destroyAllWindows()
print('Program Terminated')

import cv2

import time

from picamera2 import Picamera2

piCam = Picamera2()

W=640

H=360

tStart = time.time()

fps = 0

RES = (W,H)

piCam.preview_configuration.main.size = RES

piCam.preview_configuration.main.format = "RGB888"

piCam.preview_configuration.controls.FrameRate=60

piCam.preview_configuration.align()

piCam.configure("preview")

piCam.start()

textLowerLeft = (int(W*.01),int(H*.05))

fontFace = cv2.FONT_HERSHEY_SIMPLEX

fontThickness = int(W/425)

fontScale = H*.0015

fontColor = (0,0,255)

topBar = 65

windowWaste = 25

cv2.namedWindow("Camera", cv2.WINDOW_GUI_NORMAL)

cv2.resizeWindow("Camera", W, H)

cv2.moveWindow("Camera",0,topBar)

cv2.namedWindow("Camera Small", cv2.WINDOW_GUI_NORMAL)

cv2.resizeWindow("Camera Small", int(W/2), int(H/2))

cv2.moveWindow("Camera Small",0,topBar+windowWaste+H)

cv2.namedWindow("Gray Small", cv2.WINDOW_GUI_NORMAL)

cv2.resizeWindow("Gray Small", int(W/2), int(H/2))

cv2.moveWindow("Gray Small",int(W/2),topBar+windowWaste+H)

grays = ["Gray1","Gray2","Gray3","Gray4","Gray5"]

x = 0

for gray in grays:

print(gray)

cv2.namedWindow(gray,cv2.WINDOW_GUI_NORMAL)

cv2.resizeWindow(gray,int(W/4),int(H/4))

cv2.moveWindow(gray,W,topBar + x*(int(H/4) + windowWaste))

x=x+1

while True:

deltaT = time.time() - tStart

tStart=time.time()

fps = fps*.95 + (1/deltaT)*.05

frame= piCam.capture_array()

frame=cv2.flip(frame,-1)

frameSmall=cv2.resize(frame,(int(W/2),int(H/2)))

frameGraySmall = cv2.cvtColor(frameSmall,cv2.COLOR_BGR2GRAY)

frameTiny1 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))

frameTiny2 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))

frameTiny3= cv2.resize(frameGraySmall,(int(W/4),int(H/4)))

frameTiny4 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))

frameTiny5 = cv2.resize(frameGraySmall,(int(W/4),int(H/4)))

myText = "FPS: "+str(round(fps,1))

cv2.putText(frame,myText,textLowerLeft,fontFace,fontScale,fontColor,fontThickness)

cv2.imshow("Camera", frame)

cv2.imshow("Camera Small",frameSmall)

cv2.imshow("Gray Small",frameGraySmall)

cv2.imshow("Gray1",frameTiny1)

cv2.imshow("Gray2",frameTiny2)

cv2.imshow("Gray3",frameTiny3)

cv2.imshow("Gray4",frameTiny4)

cv2.imshow("Gray5",frameTiny5)

if cv2.waitKey(1)==ord('q'):

break

cv2.destroyAllWindows()

print('Program Terminated')

Technology Tutorials

AI on the Edge LESSON 21: Managing Multiple Windows in OpenCV on the Raspberry Pi

What You Learned in This Lesson

Making The World a Better Place One High Tech Project at a Time. Enjoy!