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.
Then:
$ npm install opencv
Examples
Face Detection
cv
API Documentation
Matrix
The matrix is the most useful base datastructure 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 recognition, cv.FACE_CASCADE is a cascade that can be used for frontal face recognition.
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 = imfindContours; // 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; // Destructively alter contour `index`contours;contours;
MIT License
The library is distributed under the MIT License - if for some reason that doesn't work for you please get in touch.