Check out example codes for "bitmap to byte array c#". It will help you in understanding the concepts better.

Code Example 1

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

Code Example 2

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();
        }
    }
}

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