图像轮廓特征检测

package com.example.opencvapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import org.opencv.android.OpenCVLoader;
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.MatOfPoint2f;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.RotatedRect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;

import java.util.ArrayList;
import java.util.List;

public class Expt_5 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expt5);

        //初始化加载OpenCV
        OpenCVLoader.initDebug();
        //通过id查找按钮
        Button button_go_home5 = findViewById(R.id.go_home5);

        //添加按钮点击响应
        button_go_home5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //界面跳转
                startActivity(new Intent(Expt_5.this,MainActivity.class));
            }
        });//
        //
        Button btn_sobel_operator = findViewById(R.id.btn_sobel_operator);
        Button btn_scharr_operator = findViewById(R.id.btn_scharr_operator);
        Button btn_laplacian_operator = findViewById(R.id.btn_laplacian_operator);
        Button btn_contour_analysis = findViewById(R.id.btn_contour_analysis);
        Button btn_restore_5 = findViewById(R.id.btn_restore_5);
        ImageView img_expt_5 =findViewById(R.id.img_expt_5);

        btn_sobel_operator.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.img_expt_52);
                Mat src = new Mat();
                Utils.bitmapToMat(bitmap,src);

                Imgproc.cvtColor(src,src,Imgproc.COLOR_RGBA2GRAY);

                Mat dst_x = new Mat();
                Mat dst_y = new Mat();

                Imgproc.Sobel(src,dst_x,CvType.CV_32F,1,0);
                Core.convertScaleAbs(dst_x,dst_x);

                Imgproc.Sobel(src,dst_y,CvType.CV_32F,0,1);
                Core.convertScaleAbs(dst_y,dst_y);

                Mat dst = new Mat();
                Core.addWeighted(dst_x,0.5,dst_y,0.5,0,dst);
                dst.convertTo(dst,CvType.CV_8U);

                Utils.matToBitmap(dst,bitmap);

                img_expt_5.setImageBitmap(bitmap);

                dst.release();
                src.release();
                dst_x.release();
                dst_y.release();

            }
        });


        btn_scharr_operator.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.original);
                Mat src = new Mat();
                Utils.bitmapToMat(bitmap,src);

                Imgproc.cvtColor(src,src,Imgproc.COLOR_RGBA2GRAY);

                Mat dst_x = new Mat();
                Mat dst_y = new Mat();

                Imgproc.Scharr(src,dst_x,CvType.CV_32F,1,0);
                Core.convertScaleAbs(dst_x,dst_x);

                Imgproc.Scharr(src,dst_y,CvType.CV_32F,0,1);
                Core.convertScaleAbs(dst_y,dst_y);

                Mat dst = new Mat();
                Core.addWeighted(dst_x,0.5,dst_y,0.5,0,dst);
                dst.convertTo(dst,CvType.CV_8U);

                Utils.matToBitmap(dst,bitmap);

                img_expt_5.setImageBitmap(bitmap);

                dst.release();
                src.release();
                dst_x.release();
                dst_y.release();
            }
        });


        btn_laplacian_operator.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.original);
                Mat src = new Mat();
                Utils.bitmapToMat(bitmap,src);

                Imgproc.cvtColor(src,src,Imgproc.COLOR_RGBA2GRAY);

                Mat dst = new Mat();

                Imgproc.Laplacian(src,dst,CvType.CV_32F,7,1,0);
                Core.convertScaleAbs(dst,dst);

                Utils.matToBitmap(dst,bitmap);

                img_expt_5.setImageBitmap(bitmap);

                dst.release();
                src.release();

            }
        });

        btn_contour_analysis.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.img_expt_51);
                Mat src = new Mat();
                Utils.bitmapToMat(bitmap,src);

                Mat gray =new Mat();
                Mat binary =new Mat();
                Mat temp =new Mat();

                Imgproc.cvtColor(src,temp,Imgproc.COLOR_RGBA2RGB);
                Imgproc.cvtColor(src,gray,Imgproc.COLOR_RGBA2GRAY);
                Imgproc.threshold(gray,binary,0,255,Imgproc.THRESH_BINARY_INV|Imgproc.THRESH_OTSU);

                List<MatOfPoint> contours = new ArrayList<>();

                Mat hierarchy = new Mat();
                Imgproc.findContours(binary, contours,hierarchy,Imgproc.RETR_TREE,
                        Imgproc.CHAIN_APPROX_SIMPLE,new Point(0, 0));

                Mat dst =new Mat();
                dst.create(temp.size(),temp.type());
                Log .i( "Bound Rect Number", "Rect Number:"+contours.size());


                for (int i = 0; i<contours.size();i++) {
                    Rect rect = Imgproc.boundingRect(contours.get(i));
                    double w = rect.width;
                    double h = rect.height;
                    double rate = Math.min(w, h) / Math.max(w, h);
                    Log.i("Bound Rect", "rate:" + rate);
                    RotatedRect minRect = Imgproc.minAreaRect(new MatOfPoint2f(contours.get(i).toArray()));
                    w = minRect.size.width;
                    h = minRect.size.height;
                    rate = Math.min(w, h) / Math.max(w, h);
                    Log.i("Min Bound Rect", "rate:" + rate);
                    double area = Imgproc.contourArea(contours.get(i), false);
                    double arclen = Imgproc.arcLength(new MatOfPoint2f(contours.get(i).toArray()), true);
                    Log.i("contourArea", "area:" + area);
                    Log.i("arcLength", "arcLength:" + arclen);
                    Imgproc.drawContours(dst, contours, i, new Scalar(255, 0, 0), 3);

                    Imgproc.rectangle(dst, rect.tl(), rect.br(), new Scalar(255, 255, 0), 3, 8, 0);

                }
                Utils.matToBitmap(dst,bitmap);

                img_expt_5.setImageBitmap(bitmap);

                dst.release();
                src.release();
            }
        });


        btn_restore_5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.original);
                img_expt_5.setImageBitmap(bitmap);
            }
        });


    }
}