OpenCV - Revision history

Mmkaram: minor grammatical errors

2025-03-20T21:56:37Z

minor grammatical errors

← Older revision		Revision as of 21:56, 20 March 2025
Line 1:		Line 1:
	[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library ~~in the world~~<ref name=":0">https://opencv.org/</ref>. It is open source under the [[wikipedia:Apache_License\|Apache License]] 2<ref>https://github.com/opencv/opencv?tab=Apache-2.0-1-ov-file#</ref>. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.		[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref name=":0">https://opencv.org/</ref>. It is open source under the [[wikipedia:Apache_License\|Apache License]] 2<ref>https://github.com/opencv/opencv?tab=Apache-2.0-1-ov-file#</ref>. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.

	Due to needing dynamically linked libraries and not having all necessary dependencies ~~being~~ packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.		Due to needing dynamically linked libraries and not having all necessary dependencies packaged with the base version of the OpenCV package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.

	== Python ==		== Python ==
Line 127:		Line 127:
	It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.		It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.

	The opencv-rust package does not include the C++ bindings, thereby requiring it to be installed alongside the package itself. Luckily, it is packaged in nixpkgs and using it is just a question of getting on our system, the crate does the rest of the work.		The opencv-rust package does not include the C++ bindings, thereby requiring it to be installed alongside the package itself. Luckily, it is packaged in nixpkgs and using it is just a question of getting it on our system, the crate does the rest of the work.

	=== Flake.nix Example ===		=== Flake.nix Example ===

Klinger: Category:Python Category:Rust added (page has specific information about these languages)

2025-03-20T14:21:26Z

Category:Python Category:Rust added (page has specific information about these languages)

← Older revision		Revision as of 14:21, 20 March 2025
Line 192:		Line 192:
	}		}
	</syntaxhighlight>		</syntaxhighlight>


			[[Category:Python]]
			[[Category:Rust]]

Mmkaram: Better references

2025-03-14T23:31:31Z

Better references

← Older revision		Revision as of 23:31, 14 March 2025
Line 1:		Line 1:
	[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref name=":0">https://opencv.org/</ref> ~~in the world. It was originally developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000~~. It is open source under the [[wikipedia:Apache_License\|Apache License]] 2. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.		[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library in the world<ref name=":0">https://opencv.org/</ref>. It is open source under the [[wikipedia:Apache_License\|Apache License]] 2<ref>https://github.com/opencv/opencv?tab=Apache-2.0-1-ov-file#</ref>. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.

	Due to needing dynamically linked libraries and not having all necessary dependencies being packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.		Due to needing dynamically linked libraries and not having all necessary dependencies being packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.

Mmkaram: Fixed grammar and improved flow

2025-03-14T23:27:36Z

Fixed grammar and improved flow

Mmkaram: Added more context to the intro and rust sections

2025-03-14T23:23:35Z

Added more context to the intro and rust sections

← Older revision		Revision as of 23:23, 14 March 2025
Line 1:		Line 1:
	[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref>https://opencv.org/</ref>. Originally developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000, it is open source under the [[wikipedia:Apache_License\|Apache License]] 2. ~~The purpose~~ of this page is to help with the initial hassle of getting OpenCV to run in development environments.		[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref name=":0">https://opencv.org/</ref>. Originally developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000, it is open source under the [[wikipedia:Apache_License\|Apache License]] 2. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.

			Due to dynamically linked libraries and not all necessary dependencies being packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.

	== Python ==		== Python ==
Line 124:		Line 126:
	== Rust ==		== Rust ==
	It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.		It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.

			The opencv-rust package does not include the C++ bindings, thereby requiring it to be installed alongside the package itself. Luckily, opencv is packaged in nixpkgs and using it is just a question of getting on our system, the crate does the rest of the work.

	=== Flake.nix Example ===		=== Flake.nix Example ===

Mmkaram: Added OpenCV page

2025-03-14T23:14:39Z

Added OpenCV page

New page

[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref>https://opencv.org/</ref>. Originally developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000, it is open source under the [[wikipedia:Apache_License|Apache License]] 2. The purpose of this page is to help with the initial hassle of getting OpenCV to run in development environments.

== Python ==
To use OpenCV with Python it is generally recommended to use the Python3XXPackage package found in [[nixpkgs]]. Although, as OpenCV is written mainly in C++<ref>https://github.com/opencv/opencv</ref>, it relies heavily on stdlibc which is generally a dynamically linked library. Attempting to run any OpenCV algorithms in Python may thereby lead to errors such as this:<syntaxhighlight lang="bash">
ImportError: libstdc++.so.6: cannot open shared object file: No such file or directory
</syntaxhighlight>There are two main ways of solving this issue, using a shell.nix or flakes.

=== Shell.nix Example ===
<syntaxhighlight lang="nix">
{ pkgs ? import <nixpkgs> {} }:

let
pythonWithOpencv = pkgs.python3.withPackages (ps: [
ps.opencv4
]);
in
pkgs.mkShell {
buildInputs = [
pythonWithOpencv
pkgs.pkg-config
pkgs.stdenv.cc.cc.lib
];

shellHook = ''
export LD_LIBRARY_PATH=${pkgs.stdenv.cc.cc.lib}/lib:$LD_LIBRARY_PATH
echo "Python with OpenCV ready (cv2 version: $(python -c 'import cv2; print(cv2.__version__)'))"
'';
}

</syntaxhighlight>

=== Flake.nix Example ===
<syntaxhighlight lang="nix">
{
description = "Python development environment with OpenCV";

inputs = {
nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
flake-utils.url = "github:numtide/flake-utils";
};

outputs = { self, nixpkgs, flake-utils, ... }:
flake-utils.lib.eachDefaultSystem (system:
let
pkgs = import nixpkgs { inherit system; };
python-with-opencv = pkgs.python3.withPackages (ps: [
ps.opencv4
]);
in {
devShell = pkgs.mkShell {
buildInputs = [
python-with-opencv
pkgs.pkg-config
pkgs.stdenv.cc.cc.lib
];

shellHook = ''
export LD_LIBRARY_PATH=${pkgs.stdenv.cc.cc.lib}/lib:$LD_LIBRARY_PATH
echo "Python environment ready with OpenCV $(python -c 'import cv2; print(cv2.__version__)')"
'';
};
}
);
}

</syntaxhighlight>Both the dev shell and flake examples only allow for the base compilation of OpenCV, there are options you may want to enable like gtk support to use functions like cv2.imshow(). To enable said flags/features, you must use [https://nixos.org/guides/nix-pills/17-nixpkgs-overriding-packages.html overrides]. Beware, this may cause a full recompilation of OpenCV because you're changing build flags and that specific combination may not be cached for your system.

=== Shell.nix Override Example ===
<syntaxhighlight lang="nix">
{ pkgs ? import <nixpkgs> {
overlays = [
(self: super: {
opencv4 = super.opencv4.override {
enableGtk3 = true;
enablePython = true;
};
})
];
}
}:

pkgs.mkShell {
buildInputs = [
(pkgs.python3.withPackages (ps: [ pkgs.opencv4 ]))
pkgs.stdenv.cc.cc.lib
];
LD_LIBRARY_PATH = "${pkgs.stdenv.cc.cc.lib}/lib";
}

</syntaxhighlight>

=== Flake.nix Override Example ===
<syntaxhighlight lang="nix">
{
inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

outputs = { self, nixpkgs }:
let
system = "x86_64-linux";
pkgs = import nixpkgs {
inherit system;
overlays = [
(final: prev: {
opencv4 = prev.opencv4.override {
enableGtk3 = true;
enablePython = true;
};
})
];
};
in {
devShells.${system}.default = pkgs.mkShell {
buildInputs = [
(pkgs.python3.withPackages (ps: [ pkgs.opencv4 ]))
pkgs.stdenv.cc.cc.lib
];
LD_LIBRARY_PATH = "${pkgs.stdenv.cc.cc.lib}/lib";
};
};
}

</syntaxhighlight>

== Rust ==
It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.

=== Flake.nix Example ===
<syntaxhighlight lang="nix">
{
inputs = {
nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
};

outputs = { self, nixpkgs }:
let
system = "x86_64-linux";
pkgs = import nixpkgs {
inherit system;
};
in
{
devShells.${system}.default = pkgs.mkShell {
buildInputs = with pkgs; [
glib
ffmpeg
libva
pkg-config
opencv
];
shellHook = ''
export LIBCLANG_PATH="${pkgs.llvmPackages.libclang.lib}/lib";
'';
};
};
}
</syntaxhighlight>You may also want to override the base package. You can do this easily with this example:

=== Flake.nix Override Example ===
<syntaxhighlight lang="nixos">
{
inputs = {
nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
};

outputs = { self, nixpkgs }:
let
system = "x86_64-linux";
pkgs = import nixpkgs {
inherit system;
config.allowUnfree = true;
};
in
{
devShells.${system}.default = pkgs.mkShell {
buildInputs = with pkgs; [
gtk2
glib
ffmpeg
libva
pkg-config
(opencv.override { enableGtk2 = true; })
];
shellHook = ''
export LIBCLANG_PATH="${pkgs.llvmPackages.libclang.lib}/lib";
'';
};
};
}
</syntaxhighlight>

← Older revision		Revision as of 23:27, 14 March 2025
Line 1:		Line 1:
	[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref name=":0">https://opencv.org/</ref>. ~~Originally~~ developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000~~, it~~ is open source under the [[wikipedia:Apache_License\|Apache License]] 2. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.		[https://opencv.org/ OpenCV] is the world's largest and most popular computer vision library<ref name=":0">https://opencv.org/</ref> in the world. It was originally developed by [https://www.intel.com/content/www/us/en/homepage.html Intel] in 2000. It is open source under the [[wikipedia:Apache_License\|Apache License]] 2. OpenCV interfaces with many languages such as C++, Python and Java<ref name=":0" />.

	Due to dynamically linked libraries and not all necessary dependencies being packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.		Due to needing dynamically linked libraries and not having all necessary dependencies being packaged with the base version of the package for all uses, this page was created to help with the initial hassle of getting OpenCV to run in development environments.

	== Python ==		== Python ==
	To use OpenCV with Python it is generally recommended to use the Python3XXPackage package found in [[nixpkgs]]. Although, as OpenCV is written mainly in C++<ref>https://github.com/opencv/opencv</ref>, it relies heavily on stdlibc which is ~~generally~~ a dynamically linked library. Attempting to run any OpenCV algorithms in Python may thereby lead to errors such as this:<syntaxhighlight lang="bash">		To use OpenCV with Python it is generally recommended to use the Python3XXPackage package found in [[nixpkgs]]. Although, as OpenCV is written mainly in C++<ref>https://github.com/opencv/opencv</ref>, it relies heavily on stdlibc which is a dynamically linked library. Attempting to run any OpenCV algorithms in Python may thereby lead to errors such as this:<syntaxhighlight lang="bash">
	ImportError: libstdc++.so.6: cannot open shared object file: No such file or directory		ImportError: libstdc++.so.6: cannot open shared object file: No such file or directory
	</syntaxhighlight>There are two main ways of solving this issue, using a shell.nix or flakes.		</syntaxhighlight>There are two main ways of solving this issue, using a shell.nix or flakes.
Line 66:		Line 66:
	}		}

	</syntaxhighlight>Both the dev shell and flake examples only allow for the base compilation of OpenCV~~, there are options you may want to~~ enable ~~like~~ gtk support to use functions like cv2.imshow()~~. To enable said flags/features, you must use~~ [https://nixos.org/guides/nix-pills/17-nixpkgs-overriding-packages.html overrides]. Beware, this may cause a full recompilation of OpenCV ~~because~~ you're changing build flags and that specific combination may not be cached for your system.		</syntaxhighlight>Both the dev shell and flake examples only allow for the base compilation of OpenCV. You can enable other flags such as gtk support to use functions like cv2.imshow() by using [https://nixos.org/guides/nix-pills/17-nixpkgs-overriding-packages.html overrides]. Beware, this may cause a full recompilation of OpenCV as you're changing build flags and that specific combination may not be cached for your system.

	=== Shell.nix Override Example ===		=== Shell.nix Override Example ===
Line 127:		Line 127:
	It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.		It is important to note that the most popular OpenCV package for rust, [https://github.com/twistedfall/opencv-rust opencv-rust], is just a series of bindings for the C++ version of OpenCV, and is thereby unsafe. Errors that occur while trying to use these bindings may just fail quietly or return an error from the underlying C++ code. There is an effort to implement most of the main computer vision algorithms entirely in rust called [https://github.com/rust-cv/cv rust-cv]. The package has not been actively maintained since July of 2023.

	The opencv-rust package does not include the C++ bindings, thereby requiring it to be installed alongside the package itself. Luckily, ~~opencv~~ is packaged in nixpkgs and using it is just a question of getting on our system, the crate does the rest of the work.		The opencv-rust package does not include the C++ bindings, thereby requiring it to be installed alongside the package itself. Luckily, it is packaged in nixpkgs and using it is just a question of getting on our system, the crate does the rest of the work.

	=== Flake.nix Example ===		=== Flake.nix Example ===