node-opencv
OpenCV bindings for Node.js. OpenCV is the defacto computer vision library - by interfacing with it natively in node, we get powerful real time vision in js.
People are using node-opencv to fly control quadrocoptors, detect faces from webcam images and annotate video streams. If you're using it for something cool, I'd love to hear about it!
Install
You'll need OpenCV 2.3.1 or newer installed before installing node-opencv. Note that OpenCV 3.x is not yet fully supported.
Specific for macOS
Install OpenCV using brew
brew tap homebrew/sciencebrew install opencv
Specific for Windows
-
Download and install OpenCV (Be sure to use a 2.4 version) @ http://opencv.org/releases.html For these instructions we will assume OpenCV is put at C:\OpenCV, but you can adjust accordingly.
-
If you haven't already, create a system variable called OPENCV_DIR and set it to C:\OpenCV\build\x64\vc12
Make sure the "x64" part matches the version of NodeJS you are using.
Also add the following to your system PATH ;%OPENCV_DIR%\bin
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Install Visual Studio 2013. Make sure to get the C++ components. You can use a different edition, just make sure OpenCV supports it, and you set the "vcxx" part of the variables above to match.
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Download peterbraden/node-opencv fork git clone https://github.com/peterbraden/node-opencv
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run npm install
$ npm install opencv
Examples
Run the examples from the parent directory.
Face Detection
cv
API Documentation
Matrix
The matrix is the most useful base data structure in OpenCV. Things like images are just matrices of pixels.
Creation
rows cols
Or if you're thinking of a Matrix as an image:
height width
Or you can use opencv to read in image files. Supported formats are in the OpenCV docs, but jpgs etc are supported.
cv cv
If you need to pipe data into an image, you can use an ImageDataStream:
var s = s fs;
If however, you have a series of images, and you wish to stream them into a stream of Matrices, you can use an ImageStream. Thus:
var s = s ardrone;
Note: Each 'data' event into the ImageStream should be a complete image buffer.
Accessing Data
var mat = 44; // Create identity matrix mat // 1 mat // [1,0,0,0]mat // [0,0,0,1]
Save
mat
or:
var buff = mat
Image Processing
imimim
Simple Drawing
imim
Object Detection
There is a shortcut method for Viola-Jones Haar Cascade object detection. This can be used for face detection etc.
mat
For convenience in face detection, cv.FACE_CASCADE is a cascade that can be used for frontal face detection.
Also:
matgoodFeaturesToTrack
Contours
matfindCountoursmatdrawContourmatdrawAllContours
Using Contours
findContours
returns a Contours
collection object, not a native array. This object provides
functions for accessing, computing with, and altering the contours contained in it.
See relevant source code and examples
var contours = im; // Count of contours in the Contours objectcontourssize; // Count of corners(verticies) of contour `index`contours; // Access vertex data of contoursforvar c = 0; c < contourssize; ++c console; forvar i = 0; i < contours; ++i var point = contours; console; // Computations of contour `index`contours;contours;contours;contours;contours;contours; // Destructively alter contour `index`contours;contours;
Face Recognization
It requires to train
then predict
. For acceptable result, the face should be cropped, grayscaled and aligned, I ignore this part so that we may focus on the api usage.
** Please ensure your OpenCV 3.2+ is configured with contrib. MacPorts user may port install opencv +contrib
**
const fs = ;const path = ;const cv = ; { let f = fs; f;} let dataDir = "./_training"; { // if model existe, load it if fs fr; return; // else train a model let samples = ; if sampleslength > 3 // There are async and sync version of training method: // .train(info, cb) // cb : standard Nan::Callback // info : [[intLabel,matrixImage],...]) // .trainSync(info) fr; fr; else console } { cv;} //using defaults: .createLBPHFaceRecognizer(radius=1, neighbors=8, grid_x=8, grid_y=8, threshold=80)const fr = ;;;
Test
Using tape. Run with command:
npm test
.
Code coverage
Using istanbul and lcov. Run with command:
make cover
Build version of opencv.node
will be generated, and coverage files will be put in coverage/
directory. These files can be remvoved automatically by running make clean
.
MIT License
The library is distributed under the MIT License - if for some reason that doesn't work for you please get in touch.