OpenCV Python Tutorial For Beginners 9 - More Mouse Event Examples in OpenCV Python

OpenCV is an image processing library created by Intel and later supported by Willow Garage and now maintained by Itseez. opencv is available on Mac, Windows, Linux. Works in C, C++, and Python.
it is Open Source and free. opencv is easy to use and install.

Starting with an overview of what the course will be covering, we move on to discussing morphological operations and practically learn how they work on images. We will then learn contrast enhancement using equalization and contrast limiting. Finally we will learn 3 methods to subtract the background from the video and implement them using OpenCV.

At the end of this course, you will have a firm grasp of Computer Vision techniques using OpenCV libraries. This course will be your gateway to the world of data science.

Feel the real power of Python and programming! The course offers you a unique approach of learning how to code by solving real world problems.

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[ಠ_ಠ-ಲಬ]

12:50 You have to put the y-coordinate first when getting the channel color, ex "blue = img[y, x, 0]", otherwise you get the diagonally mirrored pixelcolor.

[danutarejant]

That moment of hesitation and concern when you saw colors didnt match :D In line 6 to 8 is a mistake should be "blue = img[y, x, 0] [..]". If someone could explain me why we have to place "y" in the first place i would be grateful.
Good job at your videos!

[gauravbaviskar]

opencv represents images as numpy arrays conceptually we can think it as matrix of size [ ] [ ] [3] --> for coloured image of RGB color space ...so to acces any indivisual pixel located at any (x, y) point we need to provide first row number that is Y followed by coloumn number that is x ... that' why in second example we should write blue=[y, x, 0], green=[y, x, 1], red=[y, x, 0]... (simply you can use the analogy that how we access elements from matrix )

[anthonygonsalvis]

Dude, I like this series so far. Thank you very much for all your hard work. I'm really learning a lot. But from 12:30 to 13:00 in this particular video, I think you simply swept an issue under the rug! Your mouse clicks happened on certain colors but the new windows that popped up had a very different background color than the one you pointed on in your main image. Please fix this issue or at least edit your video to remove the misleading content. All other features you demonstrated are working as described.

[wasit-shafi]

see line no 6, 7, 8 you have mention the coordinates as x, y which is wrong the correct way is to mention them as y, x and the the channel i.e. 0 or 1 or 2....as far as i know about that

[gayrattangriberganov]

Will you create about OpenCV Tutorial in advanced level?

[himanshushekhar]

Color is not matching, because of x and y order, correct format is blue = img[y, x, 0] green = img[y, x, 1]
red = img[y, x, 2]

[debdiptadas]

why in bgr color format we taking img[y, x, 0] in this way?
why not in img[x, y, 0]?

[smiley]

I want to erase those line drawn in image after sometime....any idea how to do

[anupamadhikari]

I think the blue[x, y] must be blue[y, x] same with the other variables

[surbhiagrawal]

where is the use of line 9 in the code, i think circle is not displayed anywhere in the image ... for RGB channels in second window ?

[syedfawad]

how to go about if i want to remove the last line that got drawn. for example if i clicked right mouse button the previous lines should remove

[ashhadahsan]

After completing this series please do one on YOLO object detection

[mr_noob]

i have one doubt why it is giving error sometimes like index out of order

[shashwatmahapatra]

brother in vscode the points.append is not working

[SameerMalik-urgb]

Its showing attribute error please help, saying points is not defined... Please help asap

[hoald]

Hi! It's work fine with lena.jpg but i try to use another picture and got error when i click to pint with strong red
IndexError: index 313 is out of bounds for axis 1 with size 272
Someone help me explain this error
A lot of thanks <3

[vermatushant]

"Use cv2.EVENT_LBUTTONUP(in line4)" while running on laptops

[aniketyadav]

can anyone tell what is flag and param ?