object_detection.py

import cv2
import numpy as np


def nothing(x):
    pass


cv2.namedWindow("Tracking")
cv2.createTrackbar("LH", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LS", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LV", "Tracking", 0, 255, nothing)
cv2.createTrackbar("UH", "Tracking", 255, 255, nothing)
cv2.createTrackbar("US", "Tracking", 255, 255, nothing)
cv2.createTrackbar("UV", "Tracking", 255, 255, nothing)

while True:
    frame = cv2.imread('smarties.png')

    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)    #always convert image to HSV color format instead of bgr

    l_h = cv2.getTrackbarPos("LH", "Tracking")
    l_s = cv2.getTrackbarPos("LS", "Tracking")
    l_v = cv2.getTrackbarPos("LV", "Tracking")

    u_h = cv2.getTrackbarPos("UH", "Tracking")
    u_s = cv2.getTrackbarPos("US", "Tracking")
    u_v = cv2.getTrackbarPos("UV", "Tracking")

    l_b = np.array([l_h, l_s, l_v])
    u_b = np.array([u_h, u_s, u_v])

    mask = cv2.inRange(hsv, l_b, u_b)   

    res = cv2.bitwise_and(frame, frame, mask=mask) #to mask the original frame

    cv2.imshow("frame", frame)
    cv2.imshow("mask", mask)
    cv2.imshow("res", res)

    key = cv2.waitKey(1)
    if key == 27:
        break

cv2.destroyAllWindows()