meanshift.py

import cv2 as cv
import numpy as np
cap=cv.VideoCapture('slow_traffic_small.mp4')

# take the first frame of video
ret,frame=cap.read()

#set up initial location of window
x,y,width,height= 300,200,100,50
track_window=(x,y,width,height)

#define region of interest
roi=frame[y:y+height,x:x+width]
hsv_roi=cv.cvtColor(roi,cv.COLOR_BGR2HSV)
mask=cv.inRange(hsv_roi,np.array((0.,60.,32.)),np.array((180.,255.,255)))
roi_hist=cv.calcHist([hsv_roi],[0],mask,[180],[0,180])
cv.normalize(roi_hist,roi_hist,0,255,cv.NORM_MINMAX)

#setup the termination criteria,either 10 iteration or more by atleast 1 point
term_crit=(cv.TERM_CRITERIA_EPS| cv.TERM_CRITERIA_COUNT,10,1)
cv.imshow('roi',roi)

while(1):
    ret,frame=cap.read()
    if ret==True:
        hsv=cv.cvtColor(frame,cv.COLOR_BGR2HSV)
        dst=cv.calcBackProject([hsv],[0],roi_hist,[0,180],1)
        # apply meanshift to get to the new location
        ret,track_window=cv.meanShift(dst,track_window,term_crit)
        # draw on image
        x,y,w,h=track_window
        final_image=cv.rectangle(frame,(x,y),(x+w,y+h),255,3)

        cv.imshow("final_image",final_image)
        cv.imshow('dst',dst)
        k=cv.waitKey(30) &0xff
        if k=='27':
            break

    else:
        break