track_blue_blob_2.py

import cv2
import numpy as np

if __name__ == '__main__':
  stylo = cv2.imread("stylo.png")
  hsv = cv2.cvtColor(stylo, cv2.COLOR_BGR2HSV)
  maxs = np.max(np.max(hsv, axis=0), axis=0)
  mins = np.min(np.min(hsv, axis=0), axis=0)
  # on accede au device
  capture = cv2.VideoCapture(0)
  while True:
    # on capture une image
    _, frame = capture.read()

    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
    thresh = cv2.inRange(hsv, mins, maxs)

    # on recherche les contours
    contours,hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

    # quel est l'aire la plus grande ?
    max_area = 0
    for cnt in contours:
      area = cv2.contourArea(cnt)
      if area > max_area and area > 20:
        max_area = area
        best_cnt = cnt

    # on dessine le point le plus proche de nos attentes
    if max_area > 0:
      M = cv2.moments(best_cnt)
      cx,cy = int(M['m10']/M['m00']), int(M['m01']/M['m00'])
      cv2.circle(frame,(cx,cy),15,(0, 0, 255),-1)

    # et on affiche
    cv2.imshow("Track blue blob", frame)

    # si interuption clavier, on quitte le prgm
    if (cv2.waitKey(2) >= 0):
        break

  cv2.destroyAllWindows()
  cv2.VideoCapture(0).release()