In this lesson I describe how to track an object in OpenCV based on color. We use the HSV color space to make it simpler to train the model. Below, for your convenience, we include the code we develop in this lesson.

import numpy as np
import cv2
print(cv2.__version__)

def onTrack1(val):
    global hueLow
    hueLow=val
    print('Hue Low',hueLow)
def onTrack2(val):
    global hueHigh
    hueHigh=val
    print('Hue High',hueHigh)
def onTrack3(val):
    global satLow
    satLow=val
    print('Sat Low',satLow)
def onTrack4(val):
    global satHigh
    satHigh=val
    print('Sat High',satHigh)
def onTrack5(val):
    global valLow
    valLow=val
    print('Val Low',valLow)
def onTrack6(val):
    global valHigh
    valHigh=val
    print('Val High',valHigh)

width=640
height=360
cam=cv2.VideoCapture(0,cv2.CAP_DSHOW)
cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)
cam.set(cv2.CAP_PROP_FPS, 30)
cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))

cv2.namedWindow('myTracker')
cv2.moveWindow('myTracker',width,0)

hueLow=10
hueHigh=20
satLow=10
satHigh=250
valLow=10
valHigh=250

cv2.createTrackbar('Hue Low','myTracker',10,179,onTrack1)
cv2.createTrackbar('Hue High','myTracker',20,179,onTrack2)
cv2.createTrackbar('Sat Low','myTracker',10,255,onTrack3)
cv2.createTrackbar('Sat High','myTracker',250,255,onTrack4)
cv2.createTrackbar('Val Low','myTracker',10,255,onTrack5)
cv2.createTrackbar('Val High','myTracker',250,255,onTrack6)

while True:
    ignore,  frame = cam.read()
    frameHSV=cv2.cvtColor(frame,cv2.COLOR_BGR2HSV)
    lowerBound=np.array([hueLow,satLow,valLow])
    upperBound=np.array([hueHigh,satHigh,valHigh])
    myMask=cv2.inRange(frameHSV,lowerBound,upperBound)
    #myMask=cv2.bitwise_not(myMask)
    myObject=cv2.bitwise_and(frame,frame,mask=myMask)
    myObjectSmall=cv2.resize(myObject,(int(width/2),int(height/2)))
    cv2.imshow('My Object',myObjectSmall)
    cv2.moveWindow('My Object',int(width/2),int(height))
    myMaskSmall=cv2.resize(myMask,(int(width/2),int(height/2)))
    cv2.imshow('My Mask',myMaskSmall)
    cv2.moveWindow('My Mask',0,height)
    cv2.imshow('my WEBcam', frame)
    cv2.moveWindow('my WEBcam',0,0)
    if cv2.waitKey(1) & 0xff ==ord('q'):
        break
cam.release()

import numpy as np

import cv2

print(cv2.__version__)

def onTrack1(val):

global hueLow

hueLow=val

print('Hue Low',hueLow)

def onTrack2(val):

global hueHigh

hueHigh=val

print('Hue High',hueHigh)

def onTrack3(val):

global satLow

satLow=val

print('Sat Low',satLow)

def onTrack4(val):

global satHigh

satHigh=val

print('Sat High',satHigh)

def onTrack5(val):

global valLow

valLow=val

print('Val Low',valLow)

def onTrack6(val):

global valHigh

valHigh=val

print('Val High',valHigh)

width=640

height=360

cam=cv2.VideoCapture(0,cv2.CAP_DSHOW)

cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)

cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)

cam.set(cv2.CAP_PROP_FPS, 30)

cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))

cv2.namedWindow('myTracker')

cv2.moveWindow('myTracker',width,0)

hueLow=10

hueHigh=20

satLow=10

satHigh=250

valLow=10

valHigh=250

cv2.createTrackbar('Hue Low','myTracker',10,179,onTrack1)

cv2.createTrackbar('Hue High','myTracker',20,179,onTrack2)

cv2.createTrackbar('Sat Low','myTracker',10,255,onTrack3)

cv2.createTrackbar('Sat High','myTracker',250,255,onTrack4)

cv2.createTrackbar('Val Low','myTracker',10,255,onTrack5)

cv2.createTrackbar('Val High','myTracker',250,255,onTrack6)

while True:

ignore, frame = cam.read()

frameHSV=cv2.cvtColor(frame,cv2.COLOR_BGR2HSV)

lowerBound=np.array([hueLow,satLow,valLow])

upperBound=np.array([hueHigh,satHigh,valHigh])

myMask=cv2.inRange(frameHSV,lowerBound,upperBound)

#myMask=cv2.bitwise_not(myMask)

myObject=cv2.bitwise_and(frame,frame,mask=myMask)

myObjectSmall=cv2.resize(myObject,(int(width/2),int(height/2)))

cv2.imshow('My Object',myObjectSmall)

cv2.moveWindow('My Object',int(width/2),int(height))

myMaskSmall=cv2.resize(myMask,(int(width/2),int(height/2)))

cv2.imshow('My Mask',myMaskSmall)

cv2.moveWindow('My Mask',0,height)

cv2.imshow('my WEBcam', frame)

cv2.moveWindow('my WEBcam',0,0)

if cv2.waitKey(1) & 0xff ==ord('q'):

break

cam.release()

OpenCV, Python, Tutorial

Putting Text, Rectangles and Circles on Images in OpenCV for Windows

August 24, 2021 admin

In the video lesson above we show how to add text, rectangles and circles to video frames using OpenCV. Below we include the code with we developed in this lesson. Enjoy!

import cv2
print(cv2.__version__)
width=640
height=360
myRadius=30
myColor=(0,0,0)
myThick=2
fontH=2
fontT=2
myText='Paul is Boss'
myFont=cv2.FONT_HERSHEY_DUPLEX
upperLeft=(250,140)
lowerRight=(390,220)
lineW=4
cam=cv2.VideoCapture(1,cv2.CAP_DSHOW)
cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)
cam.set(cv2.CAP_PROP_FPS, 30)
cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))
while True:
    ignore,  frame = cam.read()
    frame[140:220,250:390]=(255,0,0)
    cv2.rectangle(frame,upperLeft,lowerRight,(0,255,0),lineW)
    cv2.circle(frame,(int(width/2),int(height/2)),myRadius,myColor,myThick)
    cv2.putText(frame,myText,(120,60),myFont,fontH,(0,0,255),fontT)
    cv2.imshow('my WEBcam', frame)
    cv2.moveWindow('my WEBcam',0,0)
    if cv2.waitKey(1) & 0xff ==ord('q'):
        break
cam.release()

import cv2

print(cv2.__version__)

width=640

height=360

myRadius=30

myColor=(0,0,0)

myThick=2

fontH=2

fontT=2

myText='Paul is Boss'

myFont=cv2.FONT_HERSHEY_DUPLEX

upperLeft=(250,140)

lowerRight=(390,220)

lineW=4

cam=cv2.VideoCapture(1,cv2.CAP_DSHOW)

cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)

cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)

cam.set(cv2.CAP_PROP_FPS, 30)

cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))

while True:

ignore, frame = cam.read()

frame[140:220,250:390]=(255,0,0)

cv2.rectangle(frame,upperLeft,lowerRight,(0,255,0),lineW)

cv2.circle(frame,(int(width/2),int(height/2)),myRadius,myColor,myThick)

cv2.putText(frame,myText,(120,60),myFont,fontH,(0,0,255),fontT)

cv2.imshow('my WEBcam', frame)

cv2.moveWindow('my WEBcam',0,0)

if cv2.waitKey(1) & 0xff ==ord('q'):

break

cam.release()

3D Graphics with Visual Python

Python 3D Graphics Tutorial 5: Bouncing Ball Simulation in Visual Python

August 21, 2021 admin

The program below is the code we developed in Lesson 5. It is a Vpython program that creates a 3D model of a marble bouncing in a box.

from vpython import *
from time import *
mRadius=.5
wallThickness=.1
roomWidth=12
roomDepth=20
roomHeight=2
floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)
leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
marble=sphere(radius=mRadius,color=color.red)
deltaX=.1
deltaY=.1
deltaZ=.1

xPos=0
yPos=0
zPos=0

while True:
    rate(25)

    xPos=xPos+deltaX
    yPos=yPos+deltaY
    zPos=zPos+deltaZ

    Xrme=xPos+mRadius
    Xlme=xPos-mRadius
    Ytme=yPos+mRadius
    Ybme=yPos-mRadius
    Zbme=zPos-mRadius
    Zfme=zPos+mRadius

    Rwe=roomWidth/2-wallThickness/2
    Lwe=-roomWidth/2+wallThickness/2
    Cwe=roomHeight/2-wallThickness/2
    FLOORwe=-roomHeight/2+wallThickness/2
    Bwe=-roomDepth/2+wallThickness/2
    Fwe=roomDepth/2-wallThickness/2

    if (Xrme>=Rwe or Xlme<=Lwe):
        deltaX=deltaX*(-1)

    if (Ytme>=Cwe or Ybme<=FLOORwe):
        deltaY=deltaY*(-1)

    if (Zfme>=Fwe or Zbme<=Bwe):
        deltaZ=deltaZ*(-1)

    marble.pos=vector(xPos,yPos,zPos)

from vpython import *

from time import *

mRadius=.5

wallThickness=.1

roomWidth=12

roomDepth=20

roomHeight=2

floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)

leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

marble=sphere(radius=mRadius,color=color.red)

deltaX=.1

deltaY=.1

deltaZ=.1

xPos=0

yPos=0

zPos=0

while True:

rate(25)

xPos=xPos+deltaX

yPos=yPos+deltaY

zPos=zPos+deltaZ

Xrme=xPos+mRadius

Xlme=xPos-mRadius

Ytme=yPos+mRadius

Ybme=yPos-mRadius

Zbme=zPos-mRadius

Zfme=zPos+mRadius

Rwe=roomWidth/2-wallThickness/2

Lwe=-roomWidth/2+wallThickness/2

Cwe=roomHeight/2-wallThickness/2

FLOORwe=-roomHeight/2+wallThickness/2

Bwe=-roomDepth/2+wallThickness/2

Fwe=roomDepth/2-wallThickness/2

if (Xrme>=Rwe or Xlme<=Lwe):

deltaX=deltaX*(-1)

if (Ytme>=Cwe or Ybme<=FLOORwe):

deltaY=deltaY*(-1)

if (Zfme>=Fwe or Zbme<=Bwe):

deltaZ=deltaZ*(-1)

marble.pos=vector(xPos,yPos,zPos)

3D Graphics with Visual Python

Python 3D Graphics LESSON 4: Understanding 3D Motion in Visual Python Model

August 14, 2021 admin

In this lesson we show how to make an animated ball properly bounce off a wall using Visual Python (Vpython).

from vpython import *
from time import *
mRadius=2
wallThickness=1
roomWidth=15
roomDepth=12
roomHeight=8
floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)
backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)
leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)
marble=sphere(radius=mRadius,color=color.red)
deltaX=.1
xPos=0
while True:
    rate(25)
    xPos=xPos+deltaX
    Xrme=xPos+mRadius
    Xlme=xPos-mRadius
    Rwe=roomWidth/2-wallThickness/2
    Lwe=-roomWidth/2+wallThickness/2
    if (Xrme>=Rwe or Xlme<Lwe):
        deltaX=deltaX*(-1)
    marble.pos=vector(xPos,0,0)

from vpython import *

from time import *

mRadius=2

wallThickness=1

roomWidth=15

roomDepth=12

roomHeight=8

floor=box(pos=vector(0,-roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

ceiling=box(pos=vector(0,roomHeight/2,0),size=vector(roomWidth,wallThickness,roomDepth), color=color.white)

backWall=box(pos=vector(0,0,-roomDepth/2),size=vector(roomWidth,roomHeight,wallThickness), color=color.white)

leftWall=box(pos=vector(-roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

rightWall=box(pos=vector(roomWidth/2,0,0),size=vector(wallThickness,roomHeight,roomDepth), color=color.white)

marble=sphere(radius=mRadius,color=color.red)

deltaX=.1

xPos=0

while True:

rate(25)

xPos=xPos+deltaX

Xrme=xPos+mRadius

Xlme=xPos-mRadius

Rwe=roomWidth/2-wallThickness/2

Lwe=-roomWidth/2+wallThickness/2

if (Xrme>=Rwe or Xlme<Lwe):

deltaX=deltaX*(-1)

marble.pos=vector(xPos,0,0)

Python

Faster Launch of WEBcam and Smoother Video in OpenCV on Windows

August 12, 2021 admin

This is the code we developed in Video Lesson #6 showing how to launch a webcam quicker and with less delay in OpenCV running on windows. The video above explains the code step by step, but for your convenience, I include the code below.

import cv2
print(cv2.__version__)
width=1280
height=720
cam=cv2.VideoCapture(1,cv2.CAP_DSHOW)
cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)
cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)
cam.set(cv2.CAP_PROP_FPS, 30)
cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))
while True:
    ignore,  frame = cam.read()
    cv2.imshow('my WEBcam', frame)
    cv2.moveWindow('my WEBcam',0,0)
    if cv2.waitKey(1) & 0xff ==ord('q'):
        break
cam.release()

import cv2

print(cv2.__version__)

width=1280

height=720

cam=cv2.VideoCapture(1,cv2.CAP_DSHOW)

cam.set(cv2.CAP_PROP_FRAME_WIDTH, width)

cam.set(cv2.CAP_PROP_FRAME_HEIGHT,height)

cam.set(cv2.CAP_PROP_FPS, 30)

cam.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc(*'MJPG'))

while True:

ignore, frame = cam.read()

cv2.imshow('my WEBcam', frame)

cv2.moveWindow('my WEBcam',0,0)

if cv2.waitKey(1) & 0xff ==ord('q'):

break

cam.release()

Technology Tutorials

Tracking an Object Based on Color in OpenCV

Putting Text, Rectangles and Circles on Images in OpenCV for Windows

Python 3D Graphics Tutorial 5: Bouncing Ball Simulation in Visual Python

Python 3D Graphics LESSON 4: Understanding 3D Motion in Visual Python Model

Faster Launch of WEBcam and Smoother Video in OpenCV on Windows

Making The World a Better Place One High Tech Project at a Time. Enjoy!