Here's one solution: http://www.mobileread.com/forums/showthread.php?t=10137
The GFL SDK/GFLAx (http://www.xnview.com/en/gfl.html) free library component can be used to convert PDF to image format. It works for ASP, VB, C# etc. GhostScript (http://sourceforge.net/projects/ghostscript/) is required for it to work.
Example code in C#:
{
string file = "D:/test.pdf";
string image = "D:\\test.png";
try
{
GflAx.GflAxClass g = new GflAx.GflAxClass();
g.EpsDpi = 150;
g.Page = 1;
g.LoadBitmap(file);
g.SaveFormat = GflAx.AX_SaveFormats.AX_PNG;
g.SaveBitmap(image);
MessageBox.Show(this, "PDF to PNG conversion ended");
}
catch (Exception ex) {
MessageBox.Show(this, "GflAx error: " + ex.Message);
}
}