ofxCvHaarFinder

class methods

variables

ofxCvHaarFinder allows you to check an image for a match to a Haar classifier. The Haar Classifier is a data file generated from a training process where an application is "taught" how to recognize something in different contexts. This can be things like recognizing whether a certain sound is a word being spoken by a user, whether a gesture is a certain shape, or, in the image shown below, whether a pattern of pixels constitute a face.

face detection

A very basic set-up of an application using ofxCvHaarFinder would look like so:

app::setup() {
   haarFinder.setup("haarcascade.xml"); // must be in /data/
}

app::update() {
   haarFinder.findHaarObjects(imageToExamine);
}

app::draw() {
  for(int i = 0; i < haarFinder.blobs.size(); i++) {
     ofDrawRectangle( haarFinder.blobs[i].boundingRect );
  }
}

ofxCvHaarFinder()

ofxCvHaarFinder::ofxCvHaarFinder()

Constructor.

ofxCvHaarFinder(...)

ofxCvHaarFinder::ofxCvHaarFinder(const ofxCvHaarFinder &finder)

Copy constructor.

~ofxCvHaarFinder()

ofxCvHaarFinder::~ofxCvHaarFinder()

Destructor.

draw(...)

void ofxCvHaarFinder::draw(float x, float y)

Draws any detected objects to the screen with a rectangle, like so:

Draw faces

findHaarObjects(...)

int ofxCvHaarFinder::findHaarObjects(const ofxCvGrayscaleImage &, int x, int y, int w, int h, int minWidth=0, int minHeight=0)

Takes an input ofxCvGrayscaleImage object and allows you to set the minimum width and height of areas that should be returned and a region of interest as an ofRectangle that you would like to limit haar finding to.

findHaarObjects(...)

int ofxCvHaarFinder::findHaarObjects(const ofxCvGrayscaleImage &input, int minWidth=0, int minHeight=0)

Takes an input ofxCvGrayscaleImage object and allows you to set the minimum width and height of areas that should be returned.

findHaarObjects(...)

int ofxCvHaarFinder::findHaarObjects(const ofxCvGrayscaleImage &input, ofRectangle &roi, int minWidth=0, int minHeight=0)

Takes an input ofxCvGrayscaleImage object and allows you to set the minimum width and height of areas that should be returned and a region of interest as an ofRectangle that you would like to limit haar finding to.

colorImg.setFromPixels(vidGrabber.getPixels());
grayImage = colorImg; // convert our color image to a grayscale image

faceFinder.findHaarObjects(grayImage);

for(int i = 0; i < faceFinder.blobs.size(); i++) {
    ofRectangle roi = faceFinder.blobs[i].boundingRect;
    eyeFinder.findHaarObjects(grayImage, roi);
}

findHaarObjects(...)

int ofxCvHaarFinder::findHaarObjects(ofImage &input, int minWidth=0, int minHeight=0)

Takes an input ofImage object and allows you to set the minimum width and height of areas that should be returned.

camera.grabFrame();
if(camera.isFrameNew())
{
    img.setFromPixels(grab.getPixels());
    finder.findHaarObjects(img);
}

findHaarObjects(...)

int ofxCvHaarFinder::findHaarObjects(ofPixels &input, int minWidth=0, int minHeight=0)

Takes an input ofPixels object and allows you to set the minimum width and height of areas that should be returned.

getHeight()

float ofxCvHaarFinder::getHeight()

Returns the height of the image area that is being examined.

getWidth()

float ofxCvHaarFinder::getWidth()

Returns the width of the image area that is being examined.

setNeighbors(...)

void ofxCvHaarFinder::setNeighbors(unsigned int neighbors)

Minimum number (minus 1) of neighbor rectangles that makes up an object. All the groups of a smaller number of rectangles than min_neighbors-1 are rejected. If min_neighbors is 0, the function does not any grouping at all and returns all the detected candidate rectangles, that might be useful if you want to do a customized grouping.

setScaleHaar(...)

void ofxCvHaarFinder::setScaleHaar(float scaleHaar)

setup(...)

void ofxCvHaarFinder::setup(string haarFile)

This loads a Haar cascade file into the finder. This needs to be done before the Haar finder can be used with images.

ofxCvBlob blobs

ofxCvBlob ofxCvHaarFinder::blobs

Provides access to the all the blobs detected in the last run of findHaarObjects() via a vector.

If you have any doubt about the usage of this module you can ask in the forum.

If you want to contribute better documentation or start documenting this section you can do so here

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