[版主大人啊，求]获取图片像素点颜色值问题

给你一段我编的代码，功能是变图片的分辨率，一看就明白了
Color c = new Color();
            Bitmap box1 = new Bitmap(pictureBox1.Image);
            Bitmap box2 = new Bitmap(pictureBox2.Image);
            int r, g, b, i, j, size, k1, k2, xres, yres;
            xres = pictureBox1.Image.Width;
            yres = pictureBox1.Image.Height;
            size = 2;
            for (i = 0; i < (xres - 1);i+=size)
            {
                for (j = 0; j <( yres - 1); j += size)
                {
                    c = box1.GetPixel(i,j);//取像素点
                    r = c.R;
                    g = c.G;
                    b = c.B;
                 
                    Color cc = Color.FromArgb(r,g,b);
                    for (k1 = 0; k1 <= (size - 1);k1++)
                    {
                        for (k2 = 0; k2 <= (size - 1); k2++)
                        {
                            box2.SetPixel(i+k1,j+k2,cc);//写入像素
                        }
                    }

                }
            }