how to use Clipboard.GetDataObject() in a web prgram

IDataObject data = Clipboard.GetDataObject();
//the value of data is null,and Clipboard.GetDataObject() dosen't work
//my program is a web prgram
//I'm sure there are some data in my clipboard
if (data.GetDataPresent(DataFormats.Bitmap))
{
 System.Drawing.Image image = (System.Drawing.Image)data.GetData(DataFormats.Bitmap, true);
 image.Save("test.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
}