FastBitmap.cs

delegate Color pixelMap(Color c);
delegate void pixelEach(Color c);

abstract class MyBitmap
{
        protected Bitmap bmp;
        public abstract Color getPixel(int x, int y);
        public abstract void setPixel(int x, int y, Color color);
        public abstract void Save();

        public void each(pixelEach proc)
        {
            for (int i = 0; i < bmp.Width; ++i)
                for (int j = 0; j < bmp.Height; ++j)
                {
                    proc(getPixel(i, j));
                }
        }

        public void map(pixelMap proc)
        {
            for (int i = 0; i < bmp.Width; ++i)
                for (int j = 0; j < bmp.Height; ++j)
                {
                    Color newval = proc(getPixel(i, j));
                    setPixel(i, j, newval);
                }
        }
    }

    unsafe class FastBitmap : MyBitmap
    {
        byte* imagePointer;
        BitmapData data;

        public FastBitmap(Bitmap bmp)
        {
            this.bmp = bmp;
            data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height),
                     ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

            imagePointer = (byte*)data.Scan0;
        }

        public override Color getPixel(int x, int y)
        {
            return Color.FromArgb(imagePointer[data.Stride * y + x * 4], imagePointer[data.Stride * y + x * 4 + 1], imagePointer[data.Stride * y + x * 4 + 2]);
        }

        public override void setPixel(int x, int y, Color color)
        {
            imagePointer[data.Stride * y + x * 4] = color.R;
            imagePointer[data.Stride * y + x * 4 + 1] = color.G;
            imagePointer[data.Stride * y + x * 4 + 2] = color.B;
        }

        public override void Save()
        {
            bmp.UnlockBits(data);
        }

 }