How to use .pb file of VGGFace2 in tensorflow (java) to find Face Embeddings?

Question

I'm trying to use some pre-trained model in Java. I'm using Intellij Idea and I've added library dependency of TensorFlow and Added OpenCV via project structure.

libraryDependency += "org.tensorflow" % "tensorflow" % "1.15.0"

I've downloaded the VGGFace2 pre-trained model from here, and trying to use its .pb file and find face embeddings.

Files which I get after completion of download:

/20170512-110547/20170512-110547.pb
/20170512-110547/model-20170512-110547.ckpt-250000.data-00000-of-00001
/20170512-110547/model-20170512-110547.ckpt-250000.index
/20170512-110547/model-20170512-110547.meta

Code:

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.tensorflow.*;
import java.nio.ByteBuffer;
import java.nio.FloatBuffer;
import java.nio.file.Paths;
import java.nio.file.Files;
import java.io.IOException;

public class DirectTensorflowTest {
    public static void main(String[] args) {
        // Load OpenCV library
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        // Path to the FaceNet model
        String modelDir = "/home/zaryab/Downloads/20170512-110547";

        try {
            // Read the FaceNet model graph
            byte[] graphDef = readAllBytesOrExit(Paths.get(modelDir, "20170512-110547.pb"));

            // Import the graph definition into TensorFlow Graph
            Graph g = new Graph();
            g.importGraphDef(graphDef);

            // Create a TensorFlow session with the imported graph
            try (Session s = new Session(g)) {
                // Load an image using OpenCV (replace this with your image loading logic)
                String imagePath = "/home/zaryab/Desktop/IMG_20231124_171435.jpg";
                Mat openCVMat = Imgcodecs.imread(imagePath);

                // Convert OpenCV Mat to float array
                float[] floatArray = convertMatToFloatArray(openCVMat);

                // Byte array to TensorFlow Tensor
                ByteBuffer byteBuffer = ByteBuffer.allocate(floatArray.length * Float.BYTES);
                byteBuffer.asFloatBuffer().put(floatArray);
                byte[] imageByte = byteBuffer.array();

                FloatBuffer fb = ByteBuffer.wrap(imageByte).asFloatBuffer();
                Tensor<Float> imageF = Tensor.create(new long[]{1, openCVMat.rows(), openCVMat.cols(), 1}, fb);

                Tensor<Boolean> falseTensor = Tensors.create(false);

                // Run the session to get embeddings
                Tensor<Float> result = s.runner()
                        .feed("input", imageF)
                        .feed("phase_train", falseTensor)
                        .fetch("embeddings")
                        .run()
                        .get(0)
                        .expect(Float.class);

                // Access the embeddings
                float[][] embeddings = new float[1][(int) result.shape()[1]]; // Assuming shape[1] gives the embedding size
                result.copyTo(embeddings);

                System.out.println(embeddings);

                result.close();
                imageF.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // Function to convert OpenCV Mat to float array
    public static float[] convertMatToFloatArray(Mat mat) {
        int rows = mat.rows();
        int cols = mat.cols();

        float[] floatArray = new float[rows * cols];

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                floatArray[i * cols + j] = (float) (mat.get(i, j)[0] / 255.0); // Normalize pixel values between 0 and 1
            }
        }

        return floatArray;
    }

    // Function to read all bytes from a file
    public static byte[] readAllBytesOrExit(java.nio.file.Path path) throws IOException {
        return Files.readAllBytes(path);
    }
}

I've taken some help from this github issue but still getting error:

2023-12-01 11:19:51.689467: W tensorflow/core/framework/op_kernel.cc:1651] OP_REQUIRES failed at conv_ops.cc:491 : Invalid argument: input depth must be evenly divisible by filter depth: 1 vs 3
Exception in thread "main" java.lang.IllegalArgumentException: input depth must be evenly divisible by filter depth: 1 vs 3
     [[{{node InceptionResnetV1/Conv2d_1a_3x3/convolution}}]]
    at org.tensorflow.Session.run(Native Method)
    at org.tensorflow.Session.access$100(Session.java:48)
    at org.tensorflow.Session$Runner.runHelper(Session.java:326)
    at org.tensorflow.Session$Runner.run(Session.java:276)
    at DirectTensorflowTest.main(DirectTensorflowTest.java:111)

Guide me how can I resolve above issue and successfully use this model in java using Tensorflow?