图片拼接：NullPointerException

Question

我已经运行了这段代码。结果似乎没有生成result.png：

public class ImageStitching {

    public static void main(String[] args){
        MatVector images = new MatVector(2);
        images.put(0,cvLoadImage("sample1.png"));
        images.put(1,cvLoadImage("sample2.png"));

        IplImage result = new IplImage(null);
        int status = stitcher.stitch(images,result);

        if( status == stitcher.OK )
        {
            cvSaveImage("result.png", result);
        }

       result = cvLoadImage("result.png");

       final CanvasFrame canvas = new CanvasFrame("My Image", 1);

       // Request closing of the application when the image window is closed.
       canvas.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);

       // Show image on window.
       canvas.showImage(result);

      }
}

错误是

Exception in thread "main" java.lang.NullPointerException
at com.googlecode.javacv.CanvasFrame.showImage(CanvasFrame.java:366)
    at com.googlecode.javacv.CanvasFrame.showImage(CanvasFrame.java:363)
    at ImageStitching.main(ImageStitching.java:50)

java:50 is canvas.showImage(result);

Answer 1

显然，当您调用 showImage 时，result 为空。

您的代码中的问题是您测试状态是否正常（if ( status == stitcher.OK )），然后您尝试加载文件。你的代码应该是这样的：

if ( status != stitcher.OK )
{
    std::cout << "ERROR" << std::endl;
    return 1;
}

那么您可能会发现问题来自拼接。

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此外，您无需在显示文件之前将result 写入文件。