I have an aspx page which will upload images to server harddisk from client pc
But now i need to change my program in such a way that it would allow me to resize the
You'll need to use the WebClient class to download the remote image.
After that, then you can resize it...Use DrawImage, not GetThumbnailImage. Make sure you dispose of your bitmap and graphics handles.. (use using{}). Set all quality settings to high.
You might want to take a look at the source code for my popular image resizer first... It will help you avoid some common trouble areas.