HSV | Technology Tutorials

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()

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Tag Archives: HSV

Tracking an Object Based on Color in OpenCV

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