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132 lines
2.8 KiB
Markdown
Executable File
132 lines
2.8 KiB
Markdown
Executable File
# node-opencv
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[](http://travis-ci.org/peterbraden/node-opencv)
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[OpenCV](http://opencv.willowgarage.com/wiki/) 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.
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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!
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## Install
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You'll need OpenCV 2.3.1 installed.
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Then:
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npm install opencv
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Or to build the repo:
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node-gyp rebuild
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## Examples
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### Face Detection
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cv.readImage("./examples/test.jpg", function(err, im){
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im.detectObject("./data/haarcascade_frontalface_alt.xml", {}, function(err, faces){
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for (var i=0;i<faces.length; i++){
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var x = faces[i]
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im.ellipse(x.x + x.width/2, x.y + x.height/2, x.width/2, x.height/2);
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}
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im.save('./out.jpg');
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});
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})
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## API Documentation
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### Matrix
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The [matrix](http://opencv.jp/opencv-2svn_org/cpp/core_basic_structures.html#mat) is the most useful
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base datastructure in OpenCV. Things like images are just matrices of pixels.
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#### Creation
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new Matrix(width, height)
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Or you can use opencv to read in image files. Supported formats are in the OpenCV docs, but jpgs etc are supported.
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cv.readImage(filename, function(mat){
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...
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})
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cv.readImage(buffer, function(mat){
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...
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})
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If you need to pipe data into an image, you can use an imagestream:
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var s = new cv.ImageStream()
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s.on('load', function(matrix){
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...
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})
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fs.createReadStream('./examples/test.jpg').pipe(s);
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#### Accessing Data
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var mat = new cv.Matrix.Eye(4,4); // Create identity matrix
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mat.get(0,0) // 1
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mat.row(0) // [1,0,0,0]
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mat.col(4) // [0,0,0,1]
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##### Save
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mat.save('./pic.jpg')
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or:
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var buff = mat.toBuffer()
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#### Image Processing
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im.convertGrayscale()
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im.canny(5, 300)
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im.houghLinesP()
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#### Simple Drawing
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im.ellipse(x, y)
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im.line([x1,y1], [x2, y2])
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#### Object Detection
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There is a shortcut method for
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[Viola-Jones Haar Cascade](http://www.cognotics.com/opencv/servo_2007_series/part_2/sidebar.html) object
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detection. This can be used for face detection etc.
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mat.detectObject(haar_cascade_xml, opts, function(err, matches){})
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Also:
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mat.goodFeaturesToTrack
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#### Contours
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mat.findCountours
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mat.drawContour
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mat.drawAllContours
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## MIT License
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The library is distributed under the MIT License - if for some reason that
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doesn't work for you please get in touch.
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