Python OpenCV script for HSV filtering, finding contours, and displaying the contours

vidhsvcontour.py

import cv2
import numpy as np

def nothing(n):
    pass

# Contours w/ greatest number of points
# TODO max by area
def biggestContourI(contours):
    maxVal = 0
    maxI = None
    for i in range(0, len(contours) - 1):
        if len(contours[i]) > maxVal:
            cs = contours[i]
            maxVal = len(contours[i])
            maxI = i
    return maxI
            

iLowH = 155;
iHighH = 225;
iLowS = 47; 
iHighS = 126;
iLowV = 82;
iHighV = 132;

cv2.namedWindow('Control')
cv2.createTrackbar("LowH", "Control", iLowH, 255, nothing);
cv2.createTrackbar("HighH", "Control", iHighH, 255, nothing);
cv2.createTrackbar("LowS", "Control", iLowS, 255, nothing);
cv2.createTrackbar("HighS", "Control", iHighS, 255, nothing);
cv2.createTrackbar("LowV", "Control", iLowV, 255, nothing);
cv2.createTrackbar("HighV", "Control", iHighV, 255, nothing);

cam = cv2.VideoCapture(0)

while True:
    ret_val, img = cam.read()

    lh = cv2.getTrackbarPos('LowH', 'Control')
    ls = cv2.getTrackbarPos('LowS', 'Control')
    lv = cv2.getTrackbarPos('LowV', 'Control')
    hh = cv2.getTrackbarPos('HighH', 'Control')
    hs = cv2.getTrackbarPos('HighS', 'Control')
    hv = cv2.getTrackbarPos('HighV', 'Control')

    lower = np.array([lh, ls, lv], dtype = "uint8")
    higher = np.array([hh, hs, hv], dtype = "uint8")
    
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    h, w = img.shape[:2]
    flt = cv2.inRange(hsv, lower, higher);
    
    contours0, hierarchy = cv2.findContours(flt, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    # Only draw the biggest one
    bc = biggestContourI(contours0)
    cv2.drawContours(img,contours0, bc, (0,255,0), 3)
    
    cv2.imshow('my webcam', img)
    cv2.imshow('hsv', hsv)
    cv2.imshow('flt', flt)
    
    if cv2.waitKey(1) == 27:
        break  # esc to quit
cv2.destroyAllWindows()

i was try your code, but how to fix it. thx

i was try your code, but how to fix it. thx

@Nawaytes looks like they changed the API at some point for findContours to no longer return im2. I fixed it, it should work now with Python 3.9.2 with cv2 version 4.5.1.