1，去官网下载opencv，下载的时候需要注册一个 Oracle 账户，分分钟就能注册。然后安装。我下的是4.7的。

2，找到jar包放进项目里

3，项目结构，比较简单

4，把下载的文件放进C盘

 

5，主类代码

import org.opencv.core.Core;


/**
 * @author lake
 * @date 2023/6/26
 */
public class TestMain {
    static {
        //在使用OpenCV前必须加载Core.NATIVE_LIBRARY_NAME类,否则会报错
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    }
    public static void main(String[] args) {
        String imagePath1 = "C:\\Users\\lake45\\Desktop\\yuan.jpg";
        String imagePath2 = "C:\\Users\\lake45\\Desktop\\fuben.jpg";
        ImageCompare imageCompare = new ImageCompare();
        imageCompare.CompareAndMarkDiff(imagePath1, imagePath2);
    }

}

6，工具类

import org.opencv.core.*;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
import org.opencv.utils.Converters;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @author lake
 * @date 2023/6/26
 */
public class ImageCompare {
    private boolean compareResult = false;
    private String mark = "_compareResult";

    /**
     * 比较两张图片，如不同则将不同处标记并输出到新的图片中
     *
     * @param imagePath1 图片1的路径
     * @param imagePath2 图片2的路径
     */
    public void CompareAndMarkDiff(String imagePath1, String imagePath2) {
        Mat mat1 = readMat(imagePath1);
        Mat mat2 = readMat(imagePath2);
        mat1 = Imgcodecs.imdecode(mat1, Imgcodecs.IMREAD_UNCHANGED);
        mat2 = Imgcodecs.imdecode(mat2, Imgcodecs.IMREAD_UNCHANGED);

        if (mat1.cols() == 0 || mat2.cols() == 0 || mat1.rows() == 0 || mat2.rows() == 0) {
            System.out.println("图片文件路径异常，获取的图片大小为0，无法读取");
            return;
        }
        if (mat1.cols() != mat2.cols() || mat1.rows() != mat2.rows()) {
            System.out.println("两张图片大小不同，无法比较");
            return;
        }
        mat1.convertTo(mat1, CvType.CV_8UC1);
        mat2.convertTo(mat2, CvType.CV_8UC1);
        Mat mat1_gray = new Mat();
        Imgproc.cvtColor(mat1, mat1_gray, Imgproc.COLOR_BGR2GRAY);
        Mat mat2_gray = new Mat();
        Imgproc.cvtColor(mat2, mat2_gray, Imgproc.COLOR_BGR2GRAY);
        mat1_gray.convertTo(mat1_gray, CvType.CV_32F);
        mat2_gray.convertTo(mat2_gray, CvType.CV_32F);
        double result = Imgproc.compareHist(mat1_gray, mat2_gray, Imgproc.CV_COMP_CORREL);
        if (result == 1) {
            compareResult = true;//此处结果为1则为完全相同
            return;
        }
        System.out.println("相似度数值为:" + result);
        Mat mat_result = new Mat();
        //计算两个灰度图的绝对差值，并输出到一个Mat对象中
        Core.absdiff(mat1_gray, mat2_gray, mat_result);
        //将灰度图按照阈值进行绝对值化
        mat_result.convertTo(mat_result, CvType.CV_8UC1);
        List<MatOfPoint> mat2_list = new ArrayList<MatOfPoint>();
        Mat mat2_hi = new Mat();
        //寻找轮廓图
        Imgproc.findContours(mat_result, mat2_list, mat2_hi, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);
        Mat mat_result1 = mat1;
        Mat mat_result2 = mat2;
        //使用红色标记不同点
        System.out.println(mat2_list.size());
        for (MatOfPoint matOfPoint : mat2_list) {
            Rect rect = Imgproc.boundingRect(matOfPoint);
            Imgproc.rectangle(mat_result1, rect.tl(), rect.br(), new Scalar(0, 0, 255), 2);
            Imgproc.rectangle(mat_result2, rect.tl(), rect.br(), new Scalar(0, 0, 255), 2);
        }
        String fileName1 = getFileName(imagePath1);
        String targetPath1 = getParentDir(imagePath2) + File.separator + fileName1.replace(".", mark + ".");
        String fileName2 = getFileName(imagePath2);
        String targetPath2 = getParentDir(imagePath2) + File.separator + fileName2.replace(".", mark + ".");
        //图片一的带标记的输出文件；
        writeImage(mat_result1, targetPath1);
        //图片二的带标记的输出文件；
        writeImage(mat_result2, targetPath2);
    }

    private void writeImage(Mat mat, String outPutFile) {
        MatOfByte matOfByte = new MatOfByte();
        Imgcodecs.imencode(".png", mat, matOfByte);
        byte[] byteArray = matOfByte.toArray();
        BufferedImage bufImage = null;
        try {
            InputStream in = new ByteArrayInputStream(byteArray);
            bufImage = ImageIO.read(in);
            ImageIO.write(bufImage, "png", new File(outPutFile));
        } catch (IOException | HeadlessException e) {
            e.printStackTrace();
        }
    }

    private String getFileName(String filePath) {
        File f = new File(filePath);
        return f.getName();
    }

    private String getParentDir(String filePath) {
        File f = new File(filePath);
        return f.getParent();
    }

    private Mat readMat(String filePath) {
        try {
            File file = new File(filePath);
            FileInputStream inputStream = new FileInputStream(filePath);
            byte[] byt = new byte[(int) file.length()];
            int read = inputStream.read(byt);
            List<Byte> bs = convert(byt);
            Mat mat1 = Converters.vector_char_to_Mat(bs);
            return mat1;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return new Mat();
    }

    private List<Byte> convert(byte[] byt) {
        List<Byte> bs = new ArrayList<Byte>();
        for (int i = 0; i < byt.length; i++) {
            bs.add(i, byt[i]);
        }
        return bs;
    }

}

7，效果图。如果是一张彩色和一张黑白的图片，效果就不太理想了。

资源文件刚刚提交，审核通过后会上地址。