virtual-paint.py

import cv2
import numpy as np

frameWidth = 640
frameHeight = 480
cap = cv2.VideoCapture(0)
cap.set(3,frameWidth)
cap.set(4,frameHeight)
cap.set(10,150)

# These color values taken using color-picker.py code 
myColors = [[20,134,0,179,255,255],
            [112,42,0,132,255,255]]

myColorValues = [[0,255,0],
                 [102,0,100]]

myPoints = []

def findColor(img,myColors,myColorValues):
    imgHSV = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    count = 0
    newPoints = []
    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)
        cv2.circle(imgResult,(x,y),10,myColorValues[count],cv2.FILLED)
        if x != 0 and y != 0:  
            newPoints.append([x,y,count])
        count += 1
        # cv2.imshow(str(color[0]), mask)
    return newPoints

def getContours(img):
    contours, hierarchy = cv2.findContours(img,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
    x, y, w, h = 0,0,0,0
    for cnt in contours:
        area = cv2.contourArea(cnt)  
        if area>500:
            # cv2.drawContours(imgResult,cnt,-1,(255,0,0),3)
            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

def drawOnCanvas(myPoints, myColorValues):
    for point in myPoints:
        cv2.circle(imgResult, (point[0],point[1]), 10, myColorValues[point[2]], cv2.FILLED)

while True:
    success, img = cap.read()
    imgResult = img.copy()
    newPoints = findColor(img,myColors,myColorValues)
    if len(newPoints) != 0:
        for newP in newPoints:
            myPoints.append(newP)
            # print(myPoints)
    
    if len(myPoints) != 0:
        drawOnCanvas(myPoints, myColorValues)

    cv2.imshow("Result",imgResult)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break