if (bitmap != null)
{
    newbitmap = bitmap.Clone() as Bitmap;
    Color pixel;
    int ret;
    for (int x = 0; x < newbitmap.Width; x++)
    {
        for (int y = 0; y < newbitmap.Height; y++)
        {
            pixel = newbitmap.GetPixel(x, y);
            ret = (int)(pixel.R * 0.299 + pixel.G * 0.587 + pixel.B * 0.114);
            newbitmap.SetPixel(x, y, Color.FromArgb(ret, ret, ret));
        }
    }
    pictureBox1.Image = newbitmap.Clone() as Image;
}

內(nèi)存法

內(nèi)存法是把圖像數(shù)據(jù)直接復(fù)制到內(nèi)存中，這樣程序的運(yùn)行速度就能大大提高了。

復(fù)制代碼代碼如下:

if (bitmap != null)
{
    newbitmap = bitmap.Clone() as Bitmap;
    Rectangle rect = new Rectangle(0, 0, newbitmap.Width, newbitmap.Height);
    System.Drawing.Imaging.BitmapData bmpdata = newbitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, newbitmap.PixelFormat);
    IntPtr ptr = bmpdata.Scan0;

    int bytes = newbitmap.Width * newbitmap.Height * 3;
    byte[] rgbvalues = new byte[bytes];

    System.Runtime.InteropServices.Marshal.Copy(ptr, rgbvalues, 0, bytes);

    double colortemp = 0;
    for (int i = 0; i < rgbvalues.Length; i += 3)
    {
        colortemp = rgbvalues[i + 2] * 0.299 + rgbvalues[i + 1] * 0.587 + rgbvalues[i] * 0.114;
        rgbvalues[i] = rgbvalues[i + 1] = rgbvalues[i + 2] = (byte)colortemp;
    }

    System.Runtime.InteropServices.Marshal.Copy(rgbvalues, 0, ptr, bytes);

    newbitmap.UnlockBits(bmpdata);
    pictureBox1.Image = newbitmap.Clone() as Image;
}

指針?lè)?/P>

這個(gè)方法和內(nèi)存法相似，開(kāi)始都是通過(guò)LockBits方法來(lái)獲取位圖的首地址，這個(gè)方法更簡(jiǎn)潔，直接用指針進(jìn)行位圖操作。所以對(duì)內(nèi)存的操作需要在unsafe下進(jìn)行操作。

復(fù)制代碼代碼如下:

if (bitmap != null)
{
    newbitmap = bitmap.Clone() as Bitmap;
    Rectangle rect = new Rectangle(0, 0, newbitmap.Width, newbitmap.Height);
    System.Drawing.Imaging.BitmapData bmpdata = newbitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, newbitmap.PixelFormat); 
    byte temp;

    unsafe
    {
        byte* ptr = (byte*)(bmpdata.Scan0);

        for (int x = 0; x < bmpdata.Width; x++)
        {
            for (int y = 0; y < bmpdata.Height; y++)
            {
                temp = (byte)(0.299 * ptr[2] + 0.587 * ptr[1] + 0.114 * ptr[0]);
                ptr[0] = ptr[1] = ptr[2] = temp;
                ptr += 3;
            }
            ptr += bmpdata.Stride - bmpdata.Width * 3;
        }
    }

    newbitmap.UnlockBits(bmpdata);
    pictureBox1.Image = newbitmap.Clone() as Image;
}