<!-- https://mvnrepository.com/artifact/org.bytedeco.javacpp-presets/opencv -->

<dependency>

    <groupId>org.bytedeco.javacpp-presets</groupId>

    <artifactId>opencv</artifactId>

    <version>4.0.-1.4.</version>

</dependency>

 System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        org.opencv.core.Mat grayImgMat = imread("src\\resource\\" + jTFimgName.getText(), IMREAD_GRAYSCALE);//读取为灰度图

        Imgcodecs.imwrite("src\\resource\\gray.png", grayImgMat);//保存mat对象为文件

ImageIcon grayIcon = new ImageIcon("src\\resource\\gray.png");

        grayIcon.setImage(grayIcon.getImage().getScaledInstance(, , Image.SCALE_DEFAULT));//大小 可以自由设置

        jLabGray.setIcon(grayIcon);