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Convert a bitmap into a byte array

Tags:

c#

bitmap

People also ask

How do I convert a bitmap to a byte?

In addition, you can simply convert byte array to Bitmap . var bmp = new Bitmap(new MemoryStream(imgByte)); You can also get Bitmap from file Path directly.

How do I convert an image to a Bytearray?

Read the image using the read() method of the ImageIO class. Create a ByteArrayOutputStream object. Write the image to the ByteArrayOutputStream object created above using the write() method of the ImageIO class. Finally convert the contents of the ByteArrayOutputStream to a byte array using the toByteArray() method.

Can we convert string to byte array in Java?

A String is stored as an array of Unicode characters in Java. To convert it to a byte array, we translate the sequence of characters into a sequence of bytes. For this translation, we use an instance of Charset. This class specifies a mapping between a sequence of chars and a sequence of bytes.

What is Bitmap recycle?

Bitmap. recycle() is used to free the memory of C++. If you only do that,the GC will collection the part of java and the memory of C is always used.


There are a couple ways.

ImageConverter

public static byte[] ImageToByte(Image img)
{
    ImageConverter converter = new ImageConverter();
    return (byte[])converter.ConvertTo(img, typeof(byte[]));
}

This one is convenient because it doesn't require a lot of code.

Memory Stream

public static byte[] ImageToByte2(Image img)
{
    using (var stream = new MemoryStream())
    {
        img.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
        return stream.ToArray();
    }
}

This one is equivalent to what you are doing, except the file is saved to memory instead of to disk. Although more code you have the option of ImageFormat and it can be easily modified between saving to memory or disk.

Source: http://www.vcskicks.com/image-to-byte.php


A MemoryStream can be helpful for this. You could put it in an extension method:

public static class ImageExtensions
{
    public static byte[] ToByteArray(this Image image, ImageFormat format)
    {
        using(MemoryStream ms = new MemoryStream())
        {
            image.Save(ms, format);
            return ms.ToArray();
        }
    }
}

You could just use it like:

var image = new Bitmap(10, 10);
// Draw your image
byte[] arr = image.ToByteArray(ImageFormat.Bmp);

I partially disagree with prestomanifto's answer in regards to the ImageConverter. Do not use ImageConverter. There's nothing technically wrong with it, but simply the fact that it uses boxing/unboxing from object tells me it's code from the old dark places of the .NET framework and its not ideal to use with image processing (it's overkill for converting to a byte[] at least), especially when you consider the following.

I took a look at the ImageConverter code used by the .Net framework, and internally it uses code almost identical to the one I provided above. It creates a new MemoryStream, saves the Bitmap in whatever format it was in when you provided it, and returns the array. Skip the extra overhead of creating an ImageConverter class by using MemoryStream


You can also just Marshal.Copy the bitmap data. No intermediary memorystream etc. and a fast memory copy. This should work on both 24-bit and 32-bit bitmaps.

public static byte[] BitmapToByteArray(Bitmap bitmap)
{

    BitmapData bmpdata = null;

    try
    {
        bmpdata = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, bitmap.PixelFormat);
        int numbytes = bmpdata.Stride * bitmap.Height;
        byte[] bytedata = new byte[numbytes];
        IntPtr ptr = bmpdata.Scan0;

        Marshal.Copy(ptr, bytedata, 0, numbytes);

        return bytedata;
    }
    finally
    {
        if (bmpdata != null)
            bitmap.UnlockBits(bmpdata);
    }

}

.


Save the Image to a MemoryStream and then grab the byte array.

http://msdn.microsoft.com/en-us/library/ms142148.aspx

  Byte[] data;

  using (var memoryStream = new MemoryStream())
  {
    image.Save(memoryStream, ImageFormat.Bmp);

    data = memoryStream.ToArray();
  }