I would recommend you to set ID while generating the ImageButton. Try this:
int count = 0;
foreach (string strDirectories in strImageAdress)
{
if (strDirectories.Contains('.'))
{
count ++;
imgbtnSlideShowPic = new ImageButton();
imgbtnSlideShowPic.AlternateText = @"..\Images\ImagesHome\" + strDirectories;
imgbtnSlideShowPic.ID = "imgbtn"+count.ToString();
imgbtnSlideShowPic.Height = 50;
imgbtnSlideShowPic.Width = 50;
imgbtnSlideShowPic.ImageUrl = @"..\Images\ImagesHome\" + strDirectories;
pnlSlideShowController.Controls.Add(imgbtnSlideShowPic);
imgbtnSlideShowPic.Click += new ImageClickEventHandler(imgbtnSlideShowPic_Click);
}
}
protected void imgbtnSlideShowPic_Click(object sender, EventArgs e)
{
ImageButton img = (ImageButton)sender;
string btn = img.ID;
}
--Amit