利用EmguCV比较BGR直方图

我正在尝试根据直方图相似度进行某种图像排名。我取了一张图像，需要将其直方图与图像数据库进行比较，这些图像的排序取决于它们与源图像的相似程度。这应该像过滤器一样工作，取最相似图像的子组，然后将它们与其他更准确和计算成本更高的方法(模式匹配，SURF等…)进行比较。

这背后的想法是，例如，一些图像有很多蓝色，而在库中有6张图像有很多蓝色，所以它会把这些图像排得更高。其他图片有很多黄色(蓝色和绿色)…

现在我的代码是这样的:

Image<Bgr, byte> colorCard = frame.Copy();
DenseHistogram histBlue = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
DenseHistogram histRed = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
DenseHistogram histGreen = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
Image<Gray, byte> imgBlue = colorCard[0];
Image<Gray, byte> imgRed = colorCard[1];
Image<Gray, byte> imgGreen = colorCard[2];
imgBlue._EqualizeHist();
imgRed._EqualizeHist();
imgGreen._EqualizeHist();
//Also tried whithout equalizing histograms
histBlue.Calculate(new Image<Gray, byte>[] { imgBlue }, true, null);
histRed.Calculate(new Image<Gray, byte>[] { imgRed }, true, null);
histGreen.Calculate(new Image<Gray, byte>[] { imgGreen }, true, null);
List<Match> matchList = new List<Match>();
foreach (String filename in image_paths)
{
    Image<Bgr, byte> imgToCompare = new Image<Bgr, byte>(filename);
    imgToCompare = imgToCompare.PyrDown().PyrUp().PyrDown().PyrUp();
    DenseHistogram histBlueToCompare = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
    DenseHistogram histRedToCompare = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
    DenseHistogram histGreenToCompare = new DenseHistogram(256, new RangeF(0.0f, 255.0f));
    Image<Gray, byte> imgBlueToCompare = colorCard[0];
    Image<Gray, byte> imgRedToCompare = colorCard[1];
    Image<Gray, byte> imgGreenToCompare = colorCard[2];
    imgBlueToCompare._EqualizeHist();
    imgRedToCompare._EqualizeHist();
    imgGreenToCompare._EqualizeHist();
    histBlueToCompare.Calculate(new Image<Gray, byte>[] { imgBlueToCompare }, true, null);
    histRedToCompare.Calculate(new Image<Gray, byte>[] { imgRedToCompare }, true, null);
    histGreenToCompare.Calculate(new Image<Gray, byte>[] { imgGreenToCompare }, true, null);
    double cBlue = CvInvoke.cvCompareHist(histBlue, histBlueToCompare, Emgu.CV.CvEnum.HISTOGRAM_COMP_METHOD.CV_COMP_CORREL);
    double cRed = CvInvoke.cvCompareHist(histRed, histRedToCompare, Emgu.CV.CvEnum.HISTOGRAM_COMP_METHOD.CV_COMP_CORREL);
    double cGreen = CvInvoke.cvCompareHist(histGreen, histGreenToCompare, Emgu.CV.CvEnum.HISTOGRAM_COMP_METHOD.CV_COMP_CORREL);
    double matchValue = (cBlue + cGreen + cRed) / 3.0;
    matchList.Add(new Match(matchValue, Path.GetFileNameWithoutExtension(filename)));
}
matchList = matchList.OrderBy(X => X.MatchValue).ToList<Match>();
foreach (Match m in matchList)
{
    Logger.Log(m.Card + ": " + m.MatchValue);
}

我可以比较每个颜色直方图，但不知道如何合并这些比较以获得单个值。Witch (cBlue + cGreen + cRed) / 3.0我没有得到好的结果。

我读到一个方法来做到这一点是地球移动距离(EMD)。EmguCV有一个叫做cvCalcEMD2的函数，但是我不知道如何使用它(参数意味着什么)，也找不到它的用法的例子。