Select the server component that is installed on the server that you are using.
If you don't know or are not sure, leave it on Auto Detect.
If You don't now if a server component is installed on your server You can use my DetectPage to verify if one or more component are installed on Your server.
Download the DetectPage.
Copy and run the DetectPage.asp on your site and it display a list of installed component.
If in your server no component are installed You can use this Free component to resize image:
Vije Resize Image (This is not my component so You use this component to Your own risk)
The image will be saved in the original format if Your component support the original image format otherwise the image will be saved in Jpeg format.
Some of this component save only in Jpeg format.
To see refer to the site of the component licensors.
If Your component don't support the uploaded image format the image will not be processed.