将图像转换为字节数组的最快方法

Question

I am making Remote Desktop sharing application in which I capture an image of the Desktop and Compress it and Send it to the receiver. To compress the image I need to convert it to a byte[].

Currently I am using this:

public byte[] imageToByteArray(System.Drawing.Image imageIn)
{
    MemoryStream ms = new MemoryStream();
    imageIn.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
    return  ms.ToArray();
}

public Image byteArrayToImage(byte[] byteArrayIn)
{
     MemoryStream ms = new MemoryStream(byteArrayIn);
     Image returnImage = Image.FromStream(ms);
     return returnImage;
}

But I don't like it because I have to save it in a ImageFormat and that may also use up resources (Slow Down) as well as produce different compression results.I have read on using Marshal.Copy and memcpy but I am unable to understand them.

So is there any other method to achieve this goal?

Answer 1

There is a RawFormat property of Image parameter which returns the file format of the image. You might try the following:

// extension method
public static byte[] imageToByteArray(this System.Drawing.Image image)
{
    using(var ms = new MemoryStream())
    {
        image.Save(ms, image.RawFormat);
        return ms.ToArray();
    }
}

Answer 2

So is there any other method to achieve this goal?

No. In order to convert an image to a byte array you have to specify an image format - just as you have to specify an encoding when you convert text to a byte array.

If you're worried about compression artefacts, pick a lossless format. If you're worried about CPU resources, pick a format which doesn't bother compressing - just raw ARGB pixels, for example. But of course that will lead to a larger byte array.

Note that if you pick a format which does include compression, there's no point in then compressing the byte array afterwards - it's almost certain to have no beneficial effect.

Answer 3

I'm not sure if you're going to get any huge gains for reasons Jon Skeet pointed out. However, you could try and benchmark the TypeConvert.ConvertTo method and see how it compares to using your current method.

ImageConverter converter = new ImageConverter();
byte[] imgArray = (byte[])converter.ConvertTo(imageIn, typeof(byte[]));

Answer 4

public static byte[] ReadImageFile(string imageLocation)
    {
        byte[] imageData = null;
        FileInfo fileInfo = new FileInfo(imageLocation);
        long imageFileLength = fileInfo.Length;
        FileStream fs = new FileStream(imageLocation, FileMode.Open, FileAccess.Read);
        BinaryReader br = new BinaryReader(fs);
        imageData = br.ReadBytes((int)imageFileLength);
        return imageData;
    }

Answer 5

public static class HelperExtensions
{
    //Convert Image to byte[] array:
    public static byte[] ToByteArray(this Image imageIn)
    {
        var ms = new MemoryStream();
        imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        return ms.ToArray();
    }

    //Convert byte[] array to Image:
    public static Image ToImage(this byte[] byteArrayIn)
    {
        var ms = new MemoryStream(byteArrayIn);
        var returnImage = Image.FromStream(ms);
        return returnImage;
    }
}

Answer 6

The fastest way i could find out is this :

var myArray = (byte[]) new ImageConverter().ConvertTo(InputImg, typeof(byte[]));

Hope to be useful

Answer 7

Try following Code:

public Byte[] ConvertPictureToByte(System.Drawing.Image PictureFile)
{
   using (var MemStrm = new MemoryStream())
   {
      PictureFile.Save(MemStrm,PictureFile.RawFormat);
      return  MemStrm.ToArray();
   }
}