Live Webcam Drawing using OpenCV

Last Updated : 03 Jan, 2023

Let us see how to draw the movement of objects captured by the webcam using OpenCV. Our program takes the video input from the webcam and tracks the objects we are moving. After identifying the objects, it will make contours precisely. After that, it will print all your drawing on the output screen.

python3

# importing the modules 
import cv2 
import numpy as np 
   
# set Width and Height of output Screen 
frameWidth = 640
frameHeight = 480
   
# capturing Video from Webcam 
cap = cv2.VideoCapture(0) 
cap.set(3, frameWidth) 
cap.set(4, frameHeight) 
   
# set brightness, id is 10 and 
# value can be changed accordingly 
cap.set(10,150) 
    
# object color values 
myColors = [[5, 107, 0, 19, 255, 255], 
            [133, 56, 0, 159, 156, 255], 
            [57, 76, 0, 100, 255, 255], 
            [90, 48, 0, 118, 255, 255]] 
   
# color values which will be used to paint 
# values needs to be in BGR 
myColorValues = [[51, 153, 255],           
                 [255, 0, 255], 
                 [0, 255, 0],            
                 [255, 0, 0]] 
  
# [x , y , colorId ]  
myPoints = []   
     
# function to pick color of object 
def findColor(img, myColors, myColorValues): 
  
    # converting the image to HSV format 
    imgHSV = cv2.cvtColor(img, cv2.COLOR_BGR2HSV) 
    count = 0
    newPoints = [] 
       
    # running for loop to work with all colors 
    for color in myColors: 
        lower = np.array(color[0:3]) 
        upper = np.array(color[3:6]) 
        mask = cv2.inRange(imgHSV,lower,upper) 
        x, y = getContours(mask) 
  
        # making the circles 
        cv2.circle(imgResult, (x,y), 15, 
                   myColorValues[count], cv2.FILLED) 
        if x != 0 and y != 0: 
            newPoints.append([x,y,count]) 
        count += 1
    return newPoints 
    
   
# contours function used to improve accuracy of paint 
def getContours(img): 
    _, contours, hierarchy = cv2.findContours(img, cv2.RETR_EXTERNAL, 
                                              cv2.CHAIN_APPROX_NONE) 
    x, y, w, h = 0, 0, 0, 0
       
    # working with contours 
    for cnt in contours: 
        area = cv2.contourArea(cnt) 
        if area > 500: 
            peri = cv2.arcLength(cnt, True) 
            approx = cv2.approxPolyDP(cnt, 0.02 * peri, True) 
            x, y, w, h = cv2.boundingRect(approx) 
    return x + w // 2, y 
    
   
# draws your action on virtual canvas 
def drawOnCanvas(myPoints, myColorValues): 
    for point in myPoints: 
        cv2.circle(imgResult, (point[0], point[1]), 
                   10, myColorValues[point[2]], cv2.FILLED) 
    
# running infinite while loop so that 
# program keep running until we close it 
while True: 
    success, img = cap.read() 
    imgResult = img.copy() 
  
    # finding the colors for the points 
    newPoints = findColor(img, myColors, myColorValues) 
    if len(newPoints)!= 0: 
        for newP in newPoints: 
            myPoints.append(newP) 
    if len(myPoints)!= 0: 
  
        # drawing the points 
        drawOnCanvas(myPoints, myColorValues) 
    
    # displaying output on Screen 
    cv2.imshow("Result", imgResult) 
       
    # condition to break programs execution 
    # press q to stop the execution of program 
    if cv2.waitKey(1) and 0xFF == ord('q'):  
        break