Image imgwd = this.imageList1.Images["wd.png"];

  var bytes = ImageToBytes(imgwd); 

 public byte[] ImageToBytes(Image image)

        {

            using (MemoryStream ms = new MemoryStream())

            {

                image.Save(ms, ImageFormat.Png);

                byte[] buffer = new byte[ms.Length];

                ms.Seek(, SeekOrigin.Begin);

                ms.Read(buffer, , buffer.Length);

                return buffer;

            }

        }