OpenCV，Java compareHist（）返回相同的值

Question

在openCV中，我想比较两个直方图。首先我将Bitmap转换为Mat：

Bitmap puzzleBmp = BitmapFactory.decodeFile(photoPath, options)
mat = new Mat(puzzleBmp.getHeight(), puzzleBmp.getWidth(), CvType.CV_8U, new Scalar(4));
Utils.bitmapToMat(puzzleBmp, mat);

接下来我要创建此图像的直方图：

Mat mRgba = new Mat();
Imgproc.cvtColor(mat, mRgba, Imgproc.COLOR_RGBA2RGB);

Imgproc.GaussianBlur(mRgba, mRgba, new Size(5, 5), 0, Imgproc.BORDER_DEFAULT);

Mat mHSV = new Mat();
Imgproc.cvtColor(mRgba, mHSV, Imgproc.COLOR_RGB2HSV_FULL);

Mat hist = new Mat();
int h_bins = 30; 
int s_bins = 32;

MatOfInt mHistSize = new MatOfInt (h_bins, s_bins);

MatOfFloat mRanges = new MatOfFloat(0, 179, 0, 255);
MatOfInt mChannels = new MatOfInt(0, 1);

List<Mat> lHSV = Arrays.asList(mHSV);

Mat mask2 = new Mat();
mask2  = Mat.zeros( mRgba.rows() + 2, mRgba.cols() + 2, CvType.CV_8UC1 );

Range rowRange = new Range( 1, mask2.rows() - 1 );
Range colRange = new Range( 1, mask2.cols() - 1 );

Mat mask = new Mat();
mask = mask2.submat(rowRange, colRange);


boolean accumulate = false;
Imgproc.calcHist(lHSV, mChannels, mask, hist, mHistSize, mRanges, accumulate);

Core.normalize(hist, hist, 0, 255, Core.NORM_MINMAX, -1, new Mat());

从这部分我得hist。但是当我使用两个不同的图像进行这些转换时，我总是从方法Imgproc.compareHist()得到相同的值，这意味着它们是相同的图片。