DoG返回带有尺寸的空Mat对象

Question

我正在尝试应用不同的高斯内核和不同的sigma

Mat gaussianKernel_1 = Imgproc.getGaussianKernel(3, .2, CvType.CV_32F);
Mat gaussianKernel_1 = Imgproc.getGaussianKernel(3, 2.7, CvType.CV_32F);

在灰度图像上，通过减去它们来获得高斯DoG的差异。问题是，在应用了如下所示的高斯差异之后 ，我得到了带有尺寸的黑色图像。

这是什么意思，为什么我没有得到一个mat对象包含高斯作为图像的差异

    Mat gaussianKernel_0 = Imgproc.getGaussianKernel(3, .2, CvType.CV_32F);
    if (!gaussianKernel_0.empty()) {
        Mat orignalGrayScaleGaussian = new Mat();
        Imgproc.filter2D(grayScaleMats.getMatAt(0), orignalGrayScaleGaussian, CvType.CV_32F, gaussianKernel_0);
        gauss0GrayScaleMats.newMat(orignalGrayScaleGaussian);
    }

    Mat gaussianKernel_1 = Imgproc.getGaussianKernel(3, 2.7, CvType.CV_32F);
    if (!gaussianKernel_1.empty()) {
        Mat orignalGrayScaleGaussian = new Mat();
        Imgproc.filter2D(grayScaleMats.getMatAt(0), orignalGrayScaleGaussian, CvType.CV_32F, gaussianKernel_1);
        gauss1GrayScaleMats.newMat(orignalGrayScaleGaussian);
    }

    for (int i = 0; i < 5; i++) {
        Mat pyrDownDest = new Mat();

        if (i == 0) {

            Imgproc.pyrDown(MatFactory.lastAddedObj(gauss0GrayScaleMats.getMatList()), pyrDownDest);
            downSampledMats0.newMat(pyrDownDest);
            MatFactory.writeMat(FilePathUtils.newOutputPath("downSampledMat0_" + i), MatFactory.lastAddedObj(downSampledMats0.getMatList()));

        } else {

            Imgproc.pyrDown(MatFactory.lastAddedObj(downSampledMats0.getMatList()), pyrDownDest);
            downSampledMats0.newMat(pyrDownDest);
            MatFactory.writeMat(FilePathUtils.newOutputPath("downSampledMat0_" + i), MatFactory.lastAddedObj(downSampledMats0.getMatList()));
        }
    }

    for (int i = 0; i < 5; i++) {
        Mat pyrDownDest = new Mat();

        if (i == 0) {

            Imgproc.pyrDown(MatFactory.lastAddedObj(gauss1GrayScaleMats.getMatList()), pyrDownDest);
            downSampledMats1.newMat(pyrDownDest);
            MatFactory.writeMat(FilePathUtils.newOutputPath("downSampledMat1_" + i), MatFactory.lastAddedObj(downSampledMats1.getMatList()));

        } else {

            Imgproc.pyrDown(MatFactory.lastAddedObj(downSampledMats1.getMatList()), pyrDownDest);
            downSampledMats1.newMat(pyrDownDest);
            MatFactory.writeMat(FilePathUtils.newOutputPath("downSampledMat1_" + i), MatFactory.lastAddedObj(downSampledMats1.getMatList()));
        }
    }

    Log.D(TAG, "MainClass", "downSampledMats0Size: " + downSampledMats0.getMatList().size());
    Log.D(TAG, "MainClass", "downSampledMats1Size: " + downSampledMats1.getMatList().size());

    Mat desResize0 = new Mat();
    Mat desResize1 = new Mat();
    Imgproc.resize(downSampledMats0.getMatAt(3), desResize0, downSampledMats0.getMatAt(2).size());
    Imgproc.resize(downSampledMats1.getMatAt(3), desResize1, downSampledMats1.getMatAt(2).size());


    Mat DoG = new Mat();
    Core.subtract(desResize0, desResize1, DoG);
    if (!DoG.empty()){
        MatFactory.writeMat(FilePathUtils.newOutputPath("DoG"), DoG);
    } else {
        Log.W(TAG, "MainClass", "DoG mat is empty");
    }
}