Edge Detection and Gradients - OpenCV with Python for Image and Video Analysis 10

Welcome to another OpenCV with Python tutorial. In this tutorial, we'll be covering image gradients and edge detection. Image gradients can be used to measure directional intensity, and edge detection does exactly what it sounds like: it finds edges! Bet you didn't see that one coming.

[CODEMENTAL]

Sentdex, your python, opencv tutorials are gold. Thanks for putting so much effort. After all those years your videos are still helping a lot.

[DrJohnnyCraig]

Hi Thank you for the videos but I have some clarifying thoughts:
cv2.Canny(src, low_threshold, high_threshold).
If pixel is above high_threshold it is kept,
If pixel is between high and low threshold it is kept only if it is adjacent to a kept pixel
If pixel is below low threshold it is discarded.
Low_threshold and High_threshold should not be the same.

[froblinkin]

My new years resolution is to binge watch your channel.

[vaibhavchhabra]

Can you please EXPLAIN THE PARAMETERS OF THE FUNCTIONS?

[alexfan]

Just a tip. If you do a Gaussian blur before feeding into the edge detector, you can filter out the noise, because the Gaussian is a low-pass filter.

[rahulrathnakumar]

How do you decide the datatype to use for the ddepth parameter? For a sample uint8 image that I used, using CV_64F gave me a completely black output whereas using CV_8U detected the edges of the image properly. How does this work? thanks!

[calvinbarajas]

Awesome video, thanks very much. At 4:50, are you showing horizontal edges only (sobely)? I imagine you could have also shown vertical edges by using:
cv2.imshow('sobelx', edges). Thanks for the feedback.

[ahmedhabashi]

Could you please tell me the possible changes that we can do for cv2.Laplacian() to get better results as I get almost white images with some dots in it ... Thanks in advance

[JudgeIronist]

Hi Sentdex! Thank you and your video was great that it helped me to clear some of my doubts! However, I have one thing I'm unsure of. Is it applicable if I applied hough transform to be able to find a rectangle outline, or is it possible to filter out the surroundings and only detect a rectangle frame by using canny edge functions? :)

[germancarrasco]

Lap-la-cian? It is La-pla-cian (related to the Laplace operator). The Laplace operator was named after the French mathematician Pierre-Simon de Laplace (1749–1827). Anyway. Good tutorials.

[kavehghodstinat]

Hi, Do you know how to detect each edges? like the x, y coordinates of each edges detected?

[Gaatech]

looks very cool. is there a way to create a depth map from a standard photograph

[AIinAgriculture]

hi, sir.i am working on a real-time image based herbicide applicator. I will have to detect green colour(weed) from soil background and apply herbicide. My problem is under varying lightning condition how can fix the threshold value to detect green colour. How can I make a robust system that can work under different conditions?

[MyPlaylist-xqen]

Can you create a "Hand Gesture Tutorials", that will be awesome!

[akashpanchal]

Hello, i am new in OpenCV i want to detect the number of teeth from an image using OpenCV +Python. I try to using watershed +canny edge detection algorithm but i didn't find accurate teeth count from mouth images
Is this possible to find other technique. please explain.
thank you

[mohitmhatre]

what is happening what are the lines that come when i project lash light on my camera when doing laplacian

[praveendhoni]

We have to do a project on traffic lights control using image processing by comparing original with no traffic edge detected image and traffic edge detected image. Can you please help me how to do that

[bijoypal]

Sir when I am compiling the code laplacian then I am getting error "Traceback (most recent call last):
File "D:/Image processing/Project/10edgedetection&gradient.py", line 12, in <module>
cv2.imshow('laplacian', laplacian)
cv2.error: OpenCV(4.0.0) error: (-215:Assertion failed) dst.data == (uchar*)dst_ptr in function 'cvShowImage'"
Kindly help me for sloving that problem

[subornogupta]

This works pretty well though: after converting each into a numpy array.

[Moment_Captured]

I always enjoy your videos... Can you also do Histogram Oriented Gradient too?   Thanks... FYI  Laplacian is pronounced Luh 'plahs ee uhn