Real-Time Face Recognition In Java

Real-time face recognition is the process of identifying or verifying an individual's identity in a real-time video stream. This technology has a wide range of applications, from security and surveillance systems to personalized marketing and entertainment. In this article, we will explore how to implement real-time face recognition using Java programming language.

Before we dive into the code, let's briefly discuss the approach we will be using for face recognition. The approach we will be using is based on a technique called face embedding. Face embedding involves encoding a face image into a vector of numerical values that represents the unique features of that face. This vector is then compared to a database of pre-encoded vectors to identify or verify the identity of the person in the image.

To implement real-time face recognition in Java, we will be using the following technologies:

OpenCV: OpenCV is an open-source computer vision library that provides various tools and algorithms for image and video processing. It includes functions for face detection and recognition.

FaceNet: FaceNet is a deep learning model that learns a mapping from face images to a high-dimensional vector space where distances correspond to a measure of face similarity. This model is used to encode face images into a vector of numerical values.

Steps for the Real-Time Face Recognition code

Step 1: Set up the Environment

You need to set up your environment with the necessary tools and libraries to get started. You will need to download and install the following:

Java Development Kit (JDK)

Eclipse IDE

OpenCV for Java

TensorFlow for Java

Once you have installed these tools and libraries, you are ready to start coding.

Step 2: Load the FaceNet Model

The first thing we need to do is load the FaceNet model. We will be using a pre-trained FaceNet model that is available in the TensorFlow for Java library. Here's the code to load the model:

Program

FaceNetModel.java

import org.tensorflow.Graph;
import org.tensorflow.Session;
import org.tensorflow.Tensor;
import org.tensorflow.TensorFlow;

public class FaceNetModel {

    private Graph graph;
    private Session session;
    private String modelPath;

    public FaceNetModel(String modelPath) {
        this.modelPath = modelPath;
    }

    public void loadModel() {
        graph = new Graph();
        byte[] modelBytes = readAllBytesOrExit(Paths.get(modelPath));
        graph.importGraphDef(modelBytes);
        session = new Session(graph);
    }

    public float[] getFaceEmbedding(Mat face) {
        float[] embedding = null;
        try (Tensor<Float> tensor = normalizeImage(face)) {
            Tensor<Float> output = session.runner()
                    .feed("input_1", tensor)
                    .fetch("Bottleneck_BatchNorm/batchnorm/add_1")
                    .run()
                    .get(0)
                    .expect(Float.class);
            embedding = new float[(int) output.shape()[1]];
            output.copyTo(embedding);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return embedding;
    }

    private Tensor<Float> normalizeImage(Mat mat) {
        Imgproc.cvtColor(mat, mat, Imgproc.COLOR_BGR2RGB);
        mat.convertTo(mat, CvType.CV_32F);
        Core.divide(mat, Scalar.all(255.0f), mat);
        return Tensor.create(mat.reshape(1, 160, 160, 3));
    }

    private static byte[] readAllBytesOrExit(Path path) {
        try {
            return Files.readAllBytes(path);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(-1);
        }
        return null;
    }

}

Step 3: Load the Face Recognition Database

The next step is to load the face recognition database. This database contains pre-encoded face embeddings of individuals that we want to recognize. We will store this database in a HashMap with the person's name as the key and their face embedding as the value. Here's the code to load the face recognition database:

private Map<String, float[]> faceDb = new HashMap<>();

public void loadFaceDb(String dbPath) {
    try {
        BufferedReader reader = new BufferedReader(new FileReader(dbPath));
        String line;
        while ((line = reader.readLine()) != null) {
            String[] values = line.split(",");
            String name = values[0];
            float[] embedding = Arrays.stream(values[1].split(" ")).map(Float::parseFloat).toArray(float[]::new);
            faceDb.put(name, embedding);
        }
        reader.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

This code reads the face recognition database from a CSV file where each line contains the person's name followed by their face embedding values separated by commas.

Step 4: Implement Face Recognition

Now that we have loaded the FaceNet model and the face recognition database, we can implement face recognition. The process involves detecting faces in the video stream, encoding the faces into embeddings, and comparing the embeddings to those in the face recognition database to identify or verify the person in the image.

private FaceNetModel faceNetModel = new FaceNetModel("facenet.pb");

public void recognizeFaces(Mat frame) {
    Mat gray = new Mat();
    Imgproc.cvtColor(frame, gray, Imgproc.COLOR_BGR2GRAY);
    MatOfRect faces = new MatOfRect();
    cascadeClassifier.detectMultiScale(gray, faces, 1.3, 5);

    for (Rect rect : faces.toArray()) {
        Mat face = new Mat(frame, rect);
        Imgproc.resize(face, face, new Size(160, 160));
        float[] embedding = faceNetModel.getFaceEmbedding(face);
        String name = recognizeFace(embedding);
        Imgproc.putText(frame, name, new Point(rect.x, rect.y - 10), Imgproc.FONT_HERSHEY_SIMPLEX, 1, new Scalar(0, 255, 0), 2);
        Imgproc.rectangle(frame, new Point(rect.x, rect.y), new Point(rect.x + rect.width, rect.y + rect.height), new Scalar(0, 255, 0), 2);
    }
}

private String recognizeFace(float[] embedding) {
    String name = "Unknown";
    double minDistance = Double.MAX_VALUE;
    for (Map.Entry<String, float[]> entry : faceDb.entrySet()) {
        float[] dbEmbedding = entry.getValue();
        double distance = calculateDistance(embedding, dbEmbedding);
        if (distance < minDistance) {
            minDistance = distance;
            name = entry.getKey();
        }
    }
    if (minDistance > threshold) {
        name = "Unknown";
    }
    return name;
}

private double calculateDistance(float[] embedding1, float[] embedding2) {
    double sum = 0.0;
    for (int i = 0; i < embedding1.length; i++) {
        sum += Math.pow(embedding1[i] - embedding2[i], 2);
    }
    return Math.sqrt(sum);
}

This code defines a recognizeFaces method that takes a video frame as input, detects faces in the frame using a Haar Cascade classifier, encodes each face into an embedding using the FaceNet model, and compares the embeddings to those in the face recognition database using the calculateDistance method.

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