[問題]影像處理PSNR

[m24 (m24)]

我想確認我的PSNR是否正確。
所以我以WIKI的圖來做測試
http://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio

他的Q=10, PSNR 31.45dB

因此我以此張做為測試圖，算出結果如下
寬為320的PSNR=25.0154
寬為640的PSNR=25.61
寬為800的PSNR=25.99
寬為1024的PSNR=26.575
寬為1280的PSNR=27.044
寬為2028的PSNR=28.88289

...就是沒有一個是31.45dB

以下為主要程式(我不太會排版):
--------------------------
        private void button2_Click(object sender, EventArgs e) {
            double se = 0;
            OpenFileDialog openFileDialog2 = new OpenFileDialog();
            openFileDialog2.InitialDirectory = "d:\\CODE\\images\\";

            if (openFileDialog2.ShowDialog() == DialogResult.OK) {
                ImageForm MyImage =
                    new ImageForm(openFileDialog2.FileName);//create object
                pictureBox2.Image =
                    Image.FromFile(openFileDialog2.FileName);
                CurrentImage2 = MyImage;
            }

            if (CurrentImage1 != null) {

                int[, ,] rgbData1 = CurrentImage1.getRGBData();//GEG rgb MATRIX
                int[, ,] rgbData2 = CurrentImage2.getRGBData();

                if (rgbData1.GetLength(1) == rgbData2.GetLength(1)
                       && rgbData1.GetLength(0) == rgbData2.GetLength(0)) {
                    int h = rgbData1.GetLength(1);//goat:768
                    int w = rgbData1.GetLength(0);//goat:1024
                    for (int k = 0; k < 3; k++) {
                        for (int y = 0; y < h; y++) {
                            for (int x = 0; x < w; x++) {
      se =  se +
               (rgbData1[x, y, k] - rgbData2[x, y, k]) *
                               (rgbData1[x, y, k] - rgbData2[x, y, k]);
                            }
                        }
                    }
                    double psnr, mse;
                    mse = (double)se / ((double)h * (double)w * 3);
                    psnr = 10 * (Math.Log10(255 * 255 / mse));
                    lblPSNR.Text = psnr.ToString();
                } else {
                    MessageBox.Show("請載入正確圖形");
                }
            } else {
                MessageBox.Show("請先載入圖形");
            }

        }

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◆ From: 60.249.32.1
推 rainbow001:MAX代錯?2^bit-1....
→ m24:那不是2^8-1=256-1=255麼?
→ rainbow001:你有是過單純算一種顏色嗎?
→ rainbow001:   ^試
→ rainbow001:原圖為32bit PNG,不知道c#讀出來會不會有差異?
→ m24:我用scilab取出圖中的最大值，結果是255。但VS中的C#我還試
→ m24:那我是要用2^32-1麼?
→ m24:我明天再用好了。