Edit - November 10, 2021

The most recent version of the OpenCV docs (4.5.4 at the time of this writing) has the Python signatures directly below the C++ signatures. For your specific case, the function you are interested in can be found here: https://docs.opencv.org/4.5.4/d1/d79/group__photo__denoise.html#ga4c6b0031f56ea3f98f768881279ffe93


Outdated (here for posterity)

OpenCV 3.0 beta docs are the last known stable docs for the Python functions. Unfortunately, anything after they don't show you the equivalent calls between C++ and Python. I use these as a guide, but take them with a grain of salt.

For your specific case: https://docs.opencv.org/3.0-beta/modules/photo/doc/denoising.html?highlight=denoising#fastnlmeansdenoising

Answer from rayryeng on Stack Overflow
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OpenCV
docs.opencv.org › 4.x › d6 › d00 › tutorial_py_root.html
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opencv-python · PyPI
Pre-built CPU-only OpenCV packages for Python. Check the manual build section if you wish to compile the bindings from source to enable additional modules such as CUDA. If you have previous/other manually installed (= not installed via pip) version of OpenCV installed (e.g. cv2 module in the root of Python's site-packages), remove it before installation to avoid conflicts.
      » pip install opencv-python
    
Published   Feb 05, 2026
Version   4.13.0.92
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GitHub
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GitHub - opencv/opencv: Open Source Computer Vision Library · GitHub
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Medium
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January 18, 2025 - edges = cv2.Canny(image, 100, 200) Thresholding · Thresholding is a technique used to create binary images from grayscale images. It’s widely used in document scanning and object segmentation. Binary Thresholding: This is the simplest form, where each pixel is set to 255 if its value is above a certain threshold, and 0 otherwise.
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Reddit
reddit.com › r/opencv › opencv documentation is crap
r/opencv on Reddit: OpenCV documentation is crap
January 28, 2017 -

I've used OpenCV for some time now, and I love the functionality it provides, but often I find myself searching through a function documentation only to find parts of its behavior undocumented and I have to experimentally find out how it works, especially when using OpenCV through Python or Java bindings. With every new OpenCV release, more functionality is added to the library while the documentation still lacks on older classes and functions.

I hope I'm the only one with this problem, but I feel there might be others having same issues.

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Jancy Standard Library
vovkos.github.io › doxyrest-showcase › opencv › sphinx_rtd_theme › index.html
Introduction — OpenCV Documentation
… some other helper modules, such as FLANN and Google test wrappers, Python bindings, and others. The further chapters of the document describe functionality of each module.
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GeeksforGeeks
geeksforgeeks.org › python › opencv-python-tutorial
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cv2.createBackgroundSubtractorMOG2() OpenCV is used in various real-world applications like object detection, facial recognition and real-time video analysis. Extract frames using OpenCV · Displaying the coordinates of the points clicked on the image using Python-OpenCV ·
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YouTube
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OpenCV Course - Full Tutorial with Python - YouTube
Learn everything you need to know about OpenCV in this full course for beginners. We'll start all the way from the very basics (reading images and video, ima...
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media.readthedocs.org › pdf › opencv24-python-tutorials › stable › opencv24-python-tutorials.pdf pdf
OpenCV-Python Tutorials Documentation Release 1 Alexander Mordvintsev & Abid K
Chapter 1. OpenCV-Python Tutorials ... Use the function cv2.imread() to read an image. The image should be in the working directory or a full path of image ... Second argument is a flag which specifies the way image should be read. • cv2.IMREAD_COLOR : Loads a color image.
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There is a special case where you can already create a window and load image to it later. In that case, you can specify whether window is resizable or not. It is done with the function cv2.namedWindow(). By default, the flag is cv2.WINDOW_AUTOSIZE. But if you specify flag to be cv2.WINDOW_NORMAL, ...
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Reddit
reddit.com › r/python › opencv python documentation/reference
r/Python on Reddit: OpenCV Python Documentation/Reference
November 26, 2015 -

I was wondering if anyone knows a proper reference/documentation for the OpenCV bindings for python (3.x).

If this is not available yet, would it be possible to run a doc generator over the sources? i.e. are they documented properly?

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OpenCV Python Documentation - Opencv-python tutorials documentation-Tutorials documentation release-Image | PubHTML5
November 10, 2022 - Check image below: 1.8. Machine Learning 247 OpenCV-Python Tutorials Documentation, Release 1 Now I am directly moving to the code: import numpy as np import cv2 from matplotlib import pyplot as plt X = np.random.randint(25,50,(25,2)) Y = np.random.randint(60,85,(25,2)) Z = np.vstack((X,Y)) # convert to np.float32 Z = np.float32(Z) # define criteria and apply kmeans() criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 10, 1.0) ret,label,center=cv2.kmeans(Z,2,None,criteria,10,cv2.KMEANS_RANDOM_CENTERS) # Now separate the data, Note the flatten() A = Z[label.ravel()==0] B = Z[label.ravel()==1] # Plot the data plt.scatter(A[:,0],A[:,1]) plt.scatter(B[:,0],B[:,1],c = 'r') plt.scatter(center[:,0],center[:,1],s = 80,c = 'y', marker = 's') plt.xlabel('Height'),plt.ylabel('Weight') 248 Chapter 1.
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Python
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GitHub
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Wikipedia
en.wikipedia.org › wiki › OpenCV
OpenCV - Wikipedia
January 29, 2026 - There are language bindings in Python, Java, and MATLAB/Octave. The application programming interface (API) for these interfaces can be found in the online documentation. Wrapper libraries in several languages have been developed to encourage adoption by a wider audience.