Find and Draw Contours - OpenCV 3.4 with python 3 Tutorial 19

We’re going to see in this tutorial how to find and draw the contours.
Contours are simply the boundaries of an object.
Tutorial and source code: pysource.com/20...
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[@pysource-com]

►► You can Build a Computer Vision software to DETECT and TRACK any Object.
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[@sercanalnca1962]

Meeeeen , i don’t know how many time say to thank you soo muuucchh. I am beginner for computer vision in Python. In this tutorial you teach me too much think. I am very very happy because i have some project idea in my mind.

[@aqibkhan5091]

Lots of love from India ..your channel made things much easier for me..please add some more advance projects on open CV

[@inigoelias5690]

Excellent brother, this is so useful and fascinating. Greetings from Mexico.

[@apachon]

Thanks for this video.i just started learning open cv , and this is helping a lot to understand how it works .

[@yangyong6245]

Good video!!, I learned a lot of knowledge about Contour detect.

[@peenchinggyu6024]

thank you.. ive tried it at opencv2 and python2.7 and it works too

[@4bart4ley4]

Thank you man! your so helpful! hope your channel continue to grow! subscribed and liked!

[@dasamantharaorohit2866]

awesome one bro looking for the tutorial for box shaped detection which you talked at last :) (Nice Work)

[@saeedAhmed-ck3ot]

You really helped me, I learned a lot,
thank you.

[@bhimsendabby]

Firstly I totally confused about contour but sir you really helped me so thanku sir

[@Siqiuuu]

great video!😁😁😁

[@ertancakr9432]

Thank you, This video helped me so much for my project.

[@maulanamahmuddin5826]

hi i have a problem in cv2.drawContours(frame, contours, -1, (0, 255, 0), 3)
problem: error: (-215:Assertion failed) npoints > 0 in function 'drawContours'
Can someone help me

[@zahrahaghgu6115]

Thank you so much for this practical video

[@PFstoker]

Thank you very much ! Simple and clear 😁

[@jorgeivanavaloslopez2206]

it is more efficient to take the perimeter than the area.
code:
for contour in contours:
perimeter = contour.shape[0] # We get the perimeter of each contour
if perimeter > 100:
cv2.drawContours(frame, contour, -1, (0,255,0), 3)

[@luqmansen]

Great explanation, great video, thanks a lot !

[@avachavoshi574]

Very helpful, Thank you very much!

[@chetancc]

Hi Sergio, thanks for sharing in depth knowledge. I have been following your videos since long time. Can you please let me know how can we blur this object in such way that its not clearly visible after detecting in video?

[@brunofranco3421]

Great work!

[@minhtiennguyen4870]

your video is great, thank you so much ...

[@huracan311]

many thanks i'ts perfect for my project

[@erfanebrahimi9748]

great tutorial, thank you.

[@brunofranco3421]

2023 update:
you should change it to:
contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

[@user-lk5lj6vm7o]

thank you

[@solehahnur1823]

Sir,can you help me on how to get the centre coordinate of the contour

[@TalesCembraneliDantas]

Tks again for the class...

[@aniketninawe1228]

awesome

[@mahmou6]

12:00 draw contour's if-statement if area is larger or smaller a certain value. (self-note)

[@kirangouds]

this is really great video thank you, make more videos

[@HenriqueKomoto]

Thank you! Nice video.

[@PranavArrora]

Hi , Thanks for such lucid explanation . I have a question , if we can find a center(centroid) using Moments in an image , how can we calculate the end points (width and height) in the direction of the centroid WITHOUT using minboundRect

[@Nico9538]

this video really helped

[@juandavidbarrerol1510]

Great video, I have a question, is there a way to count how many objects are a in the video ?

[@venkatasubramaniamr6982]

Hi How to identify the lower and upper value for specific color... is there any logic

[@yangyong6245]

Dear, I have one question. Please tell me about the way to set lower and Upper value.

[@karimkohel3240]

dude you're awesome

[@ujwalkaka]

great work. Could u make a tutorial on how to find the tail length of vehicles in a video? really been struggling with this problem

[@ujwalkaka]

*length from a starting point

[@pysource-com]

I might do that in the future, but still I have a lot of other material to release before that :)

[@AriBernsteinM]

Thanks, this was super helpful but why use HSV? I had trouble making my contours work using HSV but no trouble just using RGB

[@firefoxyouth]

je suis le 3700 abonnement.. You should have more :)

[@arzooranipa1807]

_ , cnts , _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
ValueError: not enough values to unpack (expected 3, got 2)
please help me to solve this error

[@ismet1574]

Could you find that error's solution?

[@bassambenidir1729]

by doing this it should work
contours, hierarchy = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)

[@RafiKhalil]

@@bassambenidir1729 Thanks brother.

[@matters8535]

I love you

[@CarstenMeyer]

Is there an easy way to compare shapes with matchShapes() but scale variant? To distinguish between objects with the same shape but different size.

[@subhranilagasti6604]

I want to find the following features -(area, centroid, orientation)of an object using open cv . Please help

[@nlimbu2520]

Thank you.

[@seyedalihejazi4926]

hi can you do a video about noise reduction and its technniches.

[@harshiths4270]

Could you elaborate on what are lower and upper blue?

[@soufien7354]

why this error
TypeError: Expected Ptr for argument 'contours'
how i solve it ?

[@beastmonster1141]

Great video! How can I localize contours for only rectangular shaped objects (license plate)?

[@pysource-com]

check one of my latest video is about shape detection, you'll find the answer you're looking for.

[@erfanebrahimi9748]

Does anyone how to apply a trained classifier to detected objects with active contour? Like a applying a classifier to detect the color of detected object.

[@AmitKumar-yq3lx]

you are awesome

[@matheobermudez7847]

good video! thanks. I got a question, how did you calculate the upper and lower blue values, because you said it just worked for you? thank you again.

[@pysource-com]

Hi Matheo, I have another video tutorial where I explain that.
Look on my channel for "HSV colorspaces"

[@matheobermudez7847]

@@pysource-com ok thank you!

[@rz1359]

Thanks

[@jeevanshrestha8888]

i want to know the position of that object.......any video.....

[@MrDiegoaz3]

Hello! Good tutorial! How can I track X and Y in order to determinate the direction?

[@pysource-com]

Hi Diego,
still it's not possible to determinate direction of the object from just this source code.
Be aware that we're only working frame by frame, with images, there is no connection between them.
what you asked it's a bit more advanced, please wait a bit and I'm going to do a video about that as well.

[@SAMETELMACI]

ı want a draw rectangle of detected object how can ı

[@egemenokur2807]

hank you soooo much

[@silaskierstein4411]

So fucking cool brah

[@aimanfariz7642]

I followed exactly this video, and I got an error:
not enough values to unpack (expected 3, got 2), can you help?

[@pysource-com]

you need to change the in the line where there is:
_, contours, _ = ...
with:
contours, _ = ...
as with newste version of Opencv 4.x it extracts only two values instead of three.

[@maumunguia6384]

How I can do this with images instead of video?
I need to get the countors of an image and then get all the points of the countors
BTW excellent video

[@kazuxkazux7630]

the same way

[@bru6626]

why cv2.findcontours is not working for me
man Im stressing now

[@adityakhopkar4938]

it's cv2.findContours()

[@abdulkerimshobbytips6817]

hello sir while i try to generate a controur i get this error "_, contours, _ = cv2.findContours(red_mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
ValueError: not enough values to unpack (expected 3, got 2)" can you help me please ?

[@gabrielmarianosantos3992]

use contours, hierarchy instead of _,contours,_

[@username_6948]

tysm

[@ivancol5576]

How can I do this on Android ?

[@pysource-com]

unfortunately I can't help you as I'm not familiar with Opencv for android.
you can check docs here opencv.org/platforms/android/

[@rusich.450]

zero dislikes lol

[@mahmouds12]

Thank you