Opencv.js - Detectmultiscale "this Exception Cannot Be Caught"

I'm trying to use facial recognition via OpenCV.js, however when I call on the detectMultiScale() method of the CascadeClassifier object I receive the error: Uncaught 6446128 - Ex

Solution 1:

Following this thread:

The xml files are "pre-built" before loading them with the load function. To achieve this it's used the function createFileFromUrl from utils.js. After that we can finally load our classifier from file.

let classifier = new cv.CascadeClassifier();  // initialize classifierlet utils = newUtils('errorMessage'); //use utils classlet faceCascadeFile = 'haarcascade_frontalface_default.xml'; // path to xml// use createFileFromUrl to "pre-build" the xml
utils.createFileFromUrl(faceCascadeFile, faceCascadeFile, () => {
    classifier.load(faceCascadeFile); // in the callback, load the cascade from file 
});

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Face Detection Other Example

TRY IT :

let src = cv.imread('canvasInput');
let gray = new cv.Mat();
cv.cvtColor(src, gray, cv.COLOR_RGBA2GRAY, 0);
let faces = new cv.RectVector();
let eyes = new cv.RectVector();
let faceCascade = new cv.CascadeClassifier();
// load pre-trained classifiers
faceCascade.load('haarcascade_frontalface_default.xml');
// detect faceslet msize = new cv.Size(0, 0);

// try to change scaleFactor  and minNeighbors values
faceCascade.detectMultiScale(gray, faces,1.05,0);
for (let i = 0; i < faces.size(); ++i) {
    let roiGray = gray.roi(faces.get(i));
    let roiSrc = src.roi(faces.get(i));
    let point1 = new cv.Point(faces.get(i).x, faces.get(i).y);
    let point2 = new cv.Point(faces.get(i).x + faces.get(i).width,
                              faces.get(i).y + faces.get(i).height);
    cv.rectangle(src, point1, point2, [255, 0, 0, 255]);
    roiGray.delete(); roiSrc.delete();
}
cv.imshow('canvasOutput', src);
src.delete(); gray.delete(); faceCascade.delete();
faces.delete(); eyes.delete();

Try to change faceCascade.detectMultiScale parameters like given examples below:

faceCascade.detectMultiScale(gray, faces,1.05,0);
faceCascade.detectMultiScale(gray, faces,1.05,1);

faceCascade.detectMultiScale(gray, faces,2,0);
faceCascade.detectMultiScale(gray, faces,2,1);

faceCascade.detectMultiScale(gray, faces,3,0);
faceCascade.detectMultiScale(gray, faces,3,1);

faceCascade.detectMultiScale(gray, faces,4,0);
faceCascade.detectMultiScale(gray, faces,4,1);

Solution 2:

The solution is

let faceCascadeFile = 'haarcascade_frontalface_default.xml'; 
utils.createFileFromUrl(faceCascadeFile, faceCascadeFile, () => {
    console.log('cascade ready to load.');
    let src = cv.imread('imageInit');
    let gray = new cv.Mat();
    cv.cvtColor(src, gray, cv.COLOR_RGBA2GRAY, 0);
    let faces = new cv.RectVector();
    let faceCascade = new cv.CascadeClassifier();
        faceCascade.load(faceCascadeFile); 
        let msize = new cv.Size(0, 0);
        faceCascade.detectMultiScale(gray, faces, 1.1, 3, 0, msize, msize); 
    }); 
}

For full code and explanation use this link Face Detection with Javascript and OpenCV

or

Human Eye Detection using Javascript and OpenCV