c# - 将C++转换为C#时，图像上DCT转换的结果不同的问题

Question

我尝试编写APP，它将对图像片段进行DCT-2转换，然后使用逆DCT-2进行转换。我在c++ / opencv中找到了尝试转换为C#的代码，但是不知何故，有时我会得到不同的结果。这是我尝试转换的代码:

for (unsigned v = 0; v < BLOCK_SIZE; ++v)
{   
    for (unsigned u = 0; u < BLOCK_SIZE; ++u)
    {   
        const double cu = (u == 0) ? 1.0 / sqrt(2) : 1.0;
        const double cv = (v == 0) ? 1.0 / sqrt(2) : 1.0;
        double dctCoeff = 0;

        for (unsigned y = 0; y < BLOCK_SIZE; ++y)
        {   
            for (unsigned x = 0; x < BLOCK_SIZE; ++x)
            {   
                double uCosFactor = cos((double)(2 * x + 1) * M_PI * (double)u / (2 * (double) BLOCK_SIZE));
                double vCosFactor = cos((double)(2 * y + 1) * M_PI * (double)v / (2 * (double) BLOCK_SIZE));
                double pixel = (double)(lenaNoseGrey.at<unsigned char>(cv::Point(x,y)));
                dctCoeff += pixel * uCosFactor * vCosFactor;
            }
        }
        dctCoeff *= (2 / (double) BLOCK_SIZE) * cu * cv;
        lenaNoseDct.at<double>(cv::Point(u,v)) = dctCoeff;
    }
}   

这是我的:

for (int v = 0; v < BLOCK_SIZE; ++v)
{   
    for (int u = 0; u < BLOCK_SIZE; ++u)
    {   

        double cu = (u == 0) ? 1.0 / Math.Sqrt(2) : 1.0;
        double cv = (v == 0) ? 1.0 / Math.Sqrt(2) : 1.0;
        double dctCoeff = 0;
        double dctCoeffAlpha = 0;

        for (int y1 = 0; y1 < BLOCK_SIZE; ++y1)
        {   
            for (int x1 = 0; x1 < BLOCK_SIZE; ++x1)
            {   
                double uCosFactor = Math.Cos((2 * x1 + 1) * Math.PI * u / (2 * (double)BLOCK_SIZE));
                double vCosFactor = Math.Cos((2 * y1 + 1) * Math.PI * v / (2 * (double)BLOCK_SIZE));
                double pixel = (double)bitmapaWy1.GetPixel((x1 + 284), (y1 + 313)).R;
                double pixelalpha = (double)bitmapaWy1.GetPixel((x1 + 284), (y1 + 313)).A;
                dctCoeff += pixel * uCosFactor * vCosFactor;
                //dctCoeffAlpha += pixelalpha * uCosFactor * vCosFactor;
                dctCoeffAlpha = pixelalpha;

            }
        }
        dctCoeffAlpha *= (2 / (double)BLOCK_SIZE) * cu * cv;
        dctCoeff *= (2 / (double)BLOCK_SIZE) * cu * cv;
        macierz[u, v] = dctCoeff;

    }
}

我在矩阵中有不同的结果，但是当我用逆代码从上面的C++代码转换矩阵时，效果很好。
你能找到我做错了什么吗？我可以发现的一个区别是使用getpixel方法，但是它是在与执行C++代码完全相同的灰度图像和图像片段上执行的。

当我再次对矩阵求逆时，我可以看到图像，但是它有很多太白或太黑的随机像素。

Answer 1

问题解决了，问题太多了，我发布的实际代码起作用了，问题出在我之后的代码上了，这是将“dctcoeff”更改为字节并且在内部循环中，因此dct的值未重置为0；

int BLOCK_SIZE = 16;
        double[,] macierz = new double[16, 16];

        for (int v = 0; v < BLOCK_SIZE; ++v)
        {
            for (int u = 0; u < BLOCK_SIZE; ++u)
            {

                 double cu = (u == 0) ? 1.0 / Math.Sqrt(2) : 1.0;
                double cv = (v == 0) ? 1.0 / Math.Sqrt(2) : 1.0;
                double dctCoeff = 0;


                for (int y1 = 0; y1 < BLOCK_SIZE; ++y1)
                {
                    for (int x1 = 0; x1 < BLOCK_SIZE; ++x1)
                    {
                        double uCosFactor = Math.Cos((2 * x1 + 1) * Math.PI * u / (2 * (double)BLOCK_SIZE));
                        double vCosFactor = Math.Cos((2 * y1 + 1) * Math.PI * v / (2 * (double)BLOCK_SIZE));
                        double pixel = bitmapaWy1.GetPixel((x1 + 284), (y1 + 313)).R;

                        dctCoeff += pixel * uCosFactor * vCosFactor;
                        //dctCoeffAlpha += pixelalpha * uCosFactor * vCosFactor;


                    }
                }

                dctCoeff *= (2 / (double)BLOCK_SIZE) * cu * cv;
                macierz[u, v] = dctCoeff;

            }
        }

这段代码就像一个魅力。我希望有好心人会使用它，因为我花了大约20个小时使它起作用。