如何将Parallel.ForEach与图像对象一起使用？

Question

Now my method is :

public static byte[] ImageToByte(Image img)
{
    byte[] byteArray = new byte[0];
    using (MemoryStream stream = new MemoryStream())
    {
        img.Save(stream, System.Drawing.Imaging.ImageFormat.Bmp);
        stream.Close();
        byteArray = stream.ToArray();
    }

    return byteArray;
}

after read this . And i still confuse and can't find a way to use this.

So my question is how to use Parallel.ForEach or Parallel anything with my method.

my goal is to speed this method by using more cores of CPU to speed this up anything advice?

ps. I not serious if i can do the parallel with my method and that not speed up anything I just want to try this and record the result Thank all your guy .

Answer 1

You can only use the parallel processing if you have multiple images.

Imagine going through seperate images in a for each loop you could do this:

Parallel.ForEach(images, img =>
    {
        byte[] byteArray = new byte[0];
        using (MemoryStream stream = new MemoryStream())
        {
            img.Save(stream, System.Drawing.Imaging.ImageFormat.Bmp);
            stream.Close();
            byteArray = stream.ToArray();
        }
    });

Answer 2

If you really want to speed up the code you could do :

            BitmapData d = image.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
            int length = Math.Abs(d.Stride) * image.Height;
            byte[] buff = new byte[length]; 
            Marshal.Copy(d.Scan0, buff, 0, length);
            image.UnlockBits(d);

            return buff;