public Bitmap RePic(Bitmap thispic, int width, int height) {
Bitmap bm = new Bitmap(width, height);//初始化一个记录后的图片的对象
int x, y, resultR, resultG, resultB;
Color pixel;
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
pixel = thispic.GetPixel(x, y); //获取当前坐标的像素值
resultR = 255 - pixel.R; //反红
resultG = 255 - pixel.G; //反绿
resultB = 255 - pixel.B; //反蓝
bm.SetPixel(x, y, Color.FromArgb(resultR, resultG, resultB)); //绘图
}
}
return bm; //返回经过处理后的图片
}

public Bitmap reversePic(Bitmap thispic) {
Bitmap src = new Bitmap(Image.FromHbitmap(thispic.GetHbitmap())); // 加载图像
BitmapData srcdat = src.LockBits(new Rectangle(Point.Empty, src.Size), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb); // 锁定位图
unsafe // 不安全代码
{
byte* pix = (byte*)srcdat.Scan0; // 像素首地址
for (int i = 0; i < srcdat.Stride * srcdat.Height; i++)
pix[i] = (byte)(255 - pix[i]);
}
src.UnlockBits(srcdat); // 解锁
return src;
}