MDT5_1_Ueberwachungssystem_G1/app/src/main/java/com/example/ueberwachungssystem/Detection/OpenCVHelper.java

package com.example.ueberwachungssystem.Detection;

import android.graphics.Bitmap;
import android.media.Image;
import android.widget.ImageView;

import androidx.annotation.NonNull;
import androidx.camera.core.ExperimentalGetImage;
import androidx.camera.core.ImageProxy;

import org.opencv.android.Utils;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;


@ExperimentalGetImage
public class OpenCVHelper {

    /** OpenCV helper methods **/
    public static Mat addGaussianBlur(Mat inputMat, Size kernelSize){
        Mat outputMat = new Mat();
        Imgproc.GaussianBlur(inputMat, outputMat, kernelSize, 0);
        return outputMat;
    }

    public static Mat addBlur(Mat inputMat, Size kernelSize){
        Mat outputMat = new Mat();
        Imgproc.blur(inputMat, outputMat, kernelSize);
        return outputMat;
    }

    public static Mat extractYChannel(@NonNull ImageProxy imgProxy) {
        Image img = imgProxy.getImage();

        assert img != null;
        ByteBuffer yBuffer = img.getPlanes()[0].getBuffer();
        byte[] yData = new byte[yBuffer.remaining()];
        yBuffer.get(yData);

        Mat yMat = new Mat(img.getHeight(), img.getWidth(), CvType.CV_8UC1);
        yMat.put(0, 0, yData);

        return yMat;
    }

    public static Mat thresholdPixels(Mat inputMat, Mat previousImage, int threshold){
        Mat diffImage = new Mat();
        Core.absdiff(inputMat, previousImage, diffImage);
        Mat binaryMat = new Mat();
        Imgproc.threshold(diffImage, binaryMat, threshold, 255, Imgproc.THRESH_BINARY);
        return binaryMat;
    }


    public static Mat thresholdContourArea(Mat inputMat, float areaThreshold){
        List<MatOfPoint> contours = new ArrayList<>();
        Mat hierarchy = new Mat();
        Imgproc.findContours(inputMat, contours, hierarchy, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);

        Mat outputMat = new Mat(inputMat.size(), inputMat.type(), new Scalar(0));
        // Iterate over the contours and draw only the larger contours on the outputMat
        for (MatOfPoint contour : contours) {
            double contourArea = Imgproc.contourArea(contour);
            if (contourArea > areaThreshold) {
                Imgproc.drawContours(outputMat, Collections.singletonList(contour), 0, new Scalar(255), -1);
            }
        }
        // Apply the outputMat as a mask to the dilatedImage
        Mat maskedImage = new Mat();
        inputMat.copyTo(maskedImage, outputMat);
        return outputMat;
    }

    public static Mat dilateBinaryMat(Mat inputMat, Size kernelSize){
        Mat dilatedMat = new Mat();
        Mat kernel = Imgproc.getStructuringElement(Imgproc.MORPH_ELLIPSE, kernelSize);
        Imgproc.dilate(inputMat, dilatedMat, kernel);
        return dilatedMat;
    }

    public static int countNonZeroPixels(Mat inputImage) {
        if (inputImage != null)
            return Core.countNonZero(inputImage);
        else
            return 0;
    }


    public static void debugMat(Mat mat, ImageView imageView) {
        if (imageView == null || mat == null)
            return;

        Bitmap bitmap = Bitmap.createBitmap(mat.cols(), mat.rows(), Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(mat, bitmap);

        // Display the bitmap in an ImageView
        imageView.setImageBitmap(bitmap);
    }
}