detect_yellow_position.py

import cv2
import numpy as np
import time
import math

# Read the camera
cap = cv2.VideoCapture(0)

# Define range of colors in HSV
lower = {'Yellow':(15,90,95)}
upper = {'Yellow':(25,220,205)}

# Define color in BGR
color = {'Yellow':(0,255,255)}

while(1):

	# Take each frame
	_, frame = cap.read()

	# Convert BGR to HSV
	hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

	# Define mask
	mask = cv2.inRange(hsv, lower['Yellow'], upper['Yellow'])

	# Find contours in the mask and initialize the current (x, y) center of the ball
	cnts = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)[-2]
	center = None
	if len(cnts) > 0:

		# Find largest contour in the ball mask
		contour = max(cnts, key = cv2.contourArea)

		# Get circle info
		((x, y), radius) = cv2.minEnclosingCircle(contour)
		M = cv2.moments(contour)
		if M["m00"] != 0:
 			center = (int(M["m10"] / M["m00"]), int(M["m01"] / M["m00"]))
		else:
			center = None
		if center != None:

			# Print position and contour
			cv2.putText(frame, 'Yellow' + str(center), (int(x-radius),int(y-radius)), cv2.FONT_HERSHEY_SIMPLEX, 0.6,color['Yellow'],2)
			cv2.drawContours(frame, [contour],0,color['Yellow'],2)		

	res = cv2.bitwise_and(frame,frame,mask= mask)	

	# Show screens
	cv2.imshow('frame',frame)
	cv2.imshow('mask',mask)
	cv2.imshow('res',res)
	
	k = cv2.waitKey(1) & 0xFF
	if k == ord("q"):
		break
cv2.destroyAllWindows()