近来研究了一下GDI+绘图的基本操作，也学到了不少东西
绘制灰色图片：
System.Drawing.Bitmap bm = new System.Drawing.Bitmap
(this.pictureBox1.Image.Width,
this.pictureBox1.Image.Height,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
System.Drawing.Bitmap bmOriginal = (Bitmap)this.pictureBox1.Image;
for(int y=0;y<bmOriginal.Height;y++)
{
for(int x=0;x<bmOriginal.Width;x++)
{
Color c=bmOriginal.GetPixel(x,y);
int red,green,blue;
red = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11);
green = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11);
blue = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11);
bm.SetPixel(x,y,Color.FromArgb(red,green,blue));
}
}
this.pictureBox1.Image = bm;
绘制反色图片：
System.Drawing.Bitmap bm = new System.Drawing.Bitmap
(this.pictureBox1.Image.Width,
this.pictureBox1.Image.Height,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
System.Drawing.Bitmap bmOriginal = (Bitmap)this.pictureBox1.Image;
for(int y=0;y<bmOriginal.Height;y++)
{
for(int x=0;x<bmOriginal.Width;x++)
{
Color c=bmOriginal.GetPixel(x,y);
int red,green,blue;
red = (int)(255-c.R);
green = (int)(255-c.G);
blue = (int)(255-c.B);
}
bm.SetPixel(x,y,Color.FromArgb(red,green,blue));
}
this.pictureBox1.Image = bm;
在使用Graphics的DrawImage方法时，graphics使用Graphics.FromImage(Image)获得，既可绘制Image.
还有许多技巧，具体参考：http://www.bobpowell.net/faqmain.htm和codeproject上的一些文章和代码