installing-node-opencv

instructions for installing Node OpenCV

Windows 8.1

1. Download OpenCV:

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http://opencv.org/downloads.html

Download version 2.4.9

(please note that I've tried 2.3.1 as mentioned in the official node-opencv repo, however, though I've been able to compile it, the DLLs don't seem to work. I speculate that it may be a VS2013 vs VS2010 compile issue, as we are using the vc12 DLL files. Hopefully there are no negative implications when using node-opencv with this newer version)

Extract and move files anywhere, I prefer just putting them on my C: root in a folder called "opencv"

2. Copy OpenCV.pc:

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There's a config file of sorts called opencv.pc hosted here on this repo. I stole it from https://github.com/notcoffeetable/node-opencv This file will provide some pointers to the various opencv libraries. Be sure to edit this file if you placed OpenCV at a different location other than C:\opencv. After or before editing, move the file to C:\opencv. It doesn't need to be here, but I thought it would make sense to put OpenCV related files here. In step 3b, you'll add an environmental variable to point to this location. If you place the file in a different folder, be sure to make note of this when you progress to step 3b.

Note: I am using 64bit Windows and 64bit Node.js. My "libdir" variable in this file reflects this location /bin/x64/vc12. If you are using x86, be sure to update this location (I've provided opencv_32bit.pc for reference). Please note that changing to 32bit is VERY important for both Node Webkit and Atom-Shell. Also be sure to make this location and the environmental var location in step 3a match as they both rely on the files here.

2. Download GTK All in One Bundle

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http://win32builder.gnome.org/gtk+-bundle_3.6.4-20131201_win64.zip

Extract and move files anywhere, I prefer just puttin them on my C: root in a folder called "gtk"

This contains things you need like pkg-config, libg, and more (seemingly even installing these components one by one may not cut it)

Note: The above link is for 64bit and I'm compiling with no issues even when targeting 32bit

3a. Add Environmental Variables:

Variable name: OPENCV_DIR

Variable value for 64bit (typical use of Node.js): C:\opencv\build\x64\vc12

Variable value for 32bit (using Atom-Shell or Node Webkit): C:\opencv\build\x64\vc12

Note: value is where you put the "opencv" folder in step 1

3b. Add Environmental Variables:

Variable name: PKG_CONFIG_PATH

Variable value: C:\opencv

Note: value is where you put the "opencv.pc" file in step 2

4. Add a PATH entry:

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Variable name: PATH

Add to path: C:\gtk\bin

Here you're adding whatever's in gtk\bin to the system path, so you can use all the libraries in bin like libg, pkg-config, etc

Note: value is where you put the "gtk" folder in step 2

5. Install Microsoft Visual Studio Express 2013

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you need the MSVS Build tools

6a. NPM Install opencv (skip to step 6b if installing for Atom-Shell)

npm install opencv --save-dev --msvs_version=2013

For some reason, npm falls back to defaulting to the VS2010 tools, which probably don't exist on your machine

(--save-dev is optional, it assumes you want to save the installed version in the package.json file, though considering the --msvs_version flag, there might not be a point in saving it in your package.json file as npm install won't be useful without the flag)

6b. APM Install for Atom-Shell

There are several ways to compile for Atom-Shell. It's important to note that we are compiling for 32 bit, and also targeting Node 0.11.x. So be sure that your environmental vars and opencv.pc files reflect the 32bit paths.

Documentation can be found here: https://github.com/atom/atom-shell/blob/master/docs/tutorial/using-native-node-modules.md

OpenCV 1.0 relies on NAN (https://www.npmjs.org/package/nan) which is an abstraction layer to help deal with changes from Node.js 0.10 to 0.11 and allow projects to compile for either versions of Node (or rather Node 0.8 through 0.12). This is just a side note as the use of NAN is seamless to the install.

Since we're using the APM way, we'll need to install the Atom code editor which comes with APM (or the Atom Package Manager). APM injects some additional parameters when compiling the C++ code. The easiest way to get APM set up is to install Atom via "Chocalatey" documented here: http://chocolatey.org/packages/atom

Once installed, and you can run "apm -v" from your command line, you are good to go. Get back into your project directory and run "apm install" (instead of the normal "npm install" you'd normally do)

Did it fail?

1. Check that your environmental variable for OpenCV points to the x86 path (not the x64 path)

2. Check that your opencv.pc file points to the x86 path (not the x64 path)

3. Copy DLLs

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At this point, npm should have installed and compiled OpenCV for Node (with tons of warnings in your console I'm sure).

If so congrats!

Unfortunately, examples won't run due to missing DLLs. When running an example script you will get the following error:

module.js:356 Module._extensions[extension](this, filename); ^ Error: The specified module could not be found.

This is due to some linkage issues during the compilation process. The linkage is essentially non-existant, meaning the compiled build/Release/opencv.node file will try to read the runtime DLLs adjacent to it. The final action you'll need to take is to copy the contents of C:\opencv\build\x64\vc12\bin to \node_modules\opencv\build\Release. If using Node Webkit or Atom-Shell, don't use the build\x64 files, instead copy the build\x86 files.

NOW you should be good to go.

Did it fail? If using Atom-Shell or Node-Webkit, be sure to have copied the 32bit/x86 DLL files in this step.

8. Final Step

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Let's do some facial recognition on the Mona Lisa (as per the included examples)

Copy the main.js file along with mona.png and haarcascade_frontalface_alt.xml from this repo into your project root

Now in the command line, from the root of your project, issue the command "node main.js".

You should now have an "out.png" file at the root of your project with a circle around the Mona Lisa's face!