Write below C# Code and pass Image and also pass file format of the image,it may be any format like Jpeg,Gif or anything.
public string Convert_ImageTo_Base64(Image image,System.Drawing.Imaging.ImageFormat format)
{
using (MemoryStream ms = new MemoryStream())
{
//First Convert Image to byte[]
image.Save(ms, format);
byte[] imageBytes = ms.ToArray();
//Then Convert byte[] to Base64 String
string base64String = Convert.ToBase64String(imageBytes);
return base64String;
}
}