今天我开始测试Java和OpenCv中检测微笑的项目。识别面部和嘴巴项目使用 haarcascade_frontalface_alt 和 haarcascade_mcs_mouth 但我不明白为什么在某些原因项目检测 Nose 作为嘴巴。 我有两种方法:

private ArrayList<Mat> detectMouth(String filename) {
    int i = 0;
    ArrayList<Mat> mouths = new ArrayList<Mat>();
    // reading image in grayscale from the given path
    image = Highgui.imread(filename, Highgui.CV_LOAD_IMAGE_GRAYSCALE);
    MatOfRect faceDetections = new MatOfRect();
    // detecting face(s) on given image and saving them to MatofRect object
    faceDetector.detectMultiScale(image, faceDetections);
    System.out.println(String.format("Detected %s faces", faceDetections.toArray().length));
    MatOfRect mouthDetections = new MatOfRect();
    // detecting mouth(s) on given image and saving them to MatOfRect object
    mouthDetector.detectMultiScale(image, mouthDetections);
    System.out.println(String.format("Detected %s mouths", mouthDetections.toArray().length));
    for (Rect face : faceDetections.toArray()) {
        Mat outFace = image.submat(face);
        // saving cropped face to picture
        Highgui.imwrite("face" + i + ".png", outFace);
        for (Rect mouth : mouthDetections.toArray()) {
            // trying to find right mouth
            // if the mouth is in the lower 2/5 of the face
            // and the lower edge of mouth is above of the face
            // and the horizontal center of the mouth is the enter of the face
            if (mouth.y > face.y + face.height * 3 / 5 && mouth.y + mouth.height < face.y + face.height
                    && Math.abs((mouth.x + mouth.width / 2)) - (face.x + face.width / 2) < face.width / 10) {
                Mat outMouth = image.submat(mouth);
                // resizing mouth to the unified size of trainSize
                Imgproc.resize(outMouth, outMouth, trainSize);
                mouths.add(outMouth);
                // saving mouth to picture 
                Highgui.imwrite("mouth" + i + ".png", outMouth);
                i++;
            }
        }
    }
    return mouths;
}

并检测微笑

private void detectSmile(ArrayList<Mat> mouths) {
        trainSVM();
        CvSVMParams params = new CvSVMParams();
        // set linear kernel (no mapping, regression is done in the original feature space)
        params.set_kernel_type(CvSVM.LINEAR);
    // train SVM with images in trainingImages, labels in trainingLabels, given params with empty samples
        clasificador = new CvSVM(trainingImages, trainingLabels, new Mat(), new Mat(), params);
        // save generated SVM to file, so we can see what it generated
        clasificador.save("svm.xml");
        // loading previously saved file
        clasificador.load("svm.xml");
        // returnin, if there aren't any samples
        if (mouths.isEmpty()) {
            System.out.println("No mouth detected");
            return;
        }
        for (Mat mouth : mouths) {
            Mat out = new Mat();
            // converting to 32 bit floating point in gray scale
            mouth.convertTo(out, CvType.CV_32FC1);
            if (clasificador.predict(out.reshape(1, 1)) == 1.0) {
                System.out.println("Detected happy face");
            } else {
                System.out.println("Detected not a happy face");
            }
        }
    }

例子:

那张照片

正确检测到这个mounth:

但在其他图片中

检测到 Nose

您认为问题是什么？

最佳答案

很可能它在你的照片上检测错误，因为面部比例(与眼睛之间的距离相比，眼睛到嘴巴的距离太长)。使用haar检测器检测嘴巴和 Nose 不是很稳定，因此算法通常使用人脸的几何模型，为每个面部特征选择最佳候选特征组合。如果没有找到候选嘴巴，一些实现甚至可以尝试根据眼睛预测嘴巴位置。

Haar 检测器并不是目前最新和最著名的特征检测工具。尝试使用可变形零件模型实现。试试这个，他们有带有高效 C++ 优化函数的 matlab 代码: https://www.ics.uci.edu/~xzhu/face/

关于java和haarcascade人脸和嘴巴检测——嘴当 Nose ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37921913/