如何将两个值的最大值设置为一个像素

我在Dimage.SetPixel"Dimage有两个参数，一个给它"它的图像扩展代码中使用了以下代码。

    private void button6_Click(object sender, EventArgs e)
    {
        if (path == null)
        {
            MessageBox.Show("Please load an image");
            return;
        }
        System.Drawing.Bitmap imageX = new Bitmap(pb1.Image);
        System.Drawing.Bitmap image = AForge.Imaging.Image.Clone
            (imageX, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
        ConservativeSmoothing filterX = new ConservativeSmoothing();
        filterX.ApplyInPlace(image);
        Grayscale filter = new Grayscale(0.2125, 0.7154, 0.0721);
        Bitmap grayImage = filter.Apply(image);
        int temp;
        var imW = image.Width;
        var imH = image.Height;
        Bitmap Dimage = grayImage;
        for (int i = 1; i <= imW; i++)
        {
            for (int j = 2; j <= imH-1; j++)
            {
             temp = Math.Max(Convert.ToInt32(grayImage.GetPixel(i, j - 1)), Convert.ToInt32(grayImage.GetPixel(i, j)));
             Dimage.SetPixel(i,j) = Math.Max(temp, Convert.ToInt32(grayImage.GetPixel(i, j + 1)));
            }
        }