Using server scripts
If your server supports ASP.NET or PHP, we recommend that you use server scripts to create thumbnails and load images. Using these files will improve the quality of images and increase the speed of their loading, because images are scaled at the server and sent to the client of the necessary size. It allows you to use images of the original size or any size as well. There is no need to create thumbnails beforehand.
Note: thumbnails can be creaetd in several ways - using Server scripts (thumb.php or thumb.apsx) to create thumbnails. OR you can create thumbs using your own images, through thumb attribute and set link to this file, which will be used as a thumbnail. If the server scripts are turned off and you didn't specify thumb attribute, so thumbnails will be created from the main (original) images.
To use the script - open the Wizard (Right click on Flash Object, then FlashDevlopment24 Wizard -> Flash Image Gallery) -> 'Thumbnails' and specify the path to thumb.aspx (or thumb.php) in parameter 'Scale script'.
If your server doesn't support ASP.NET or PHP, so you just need clear parameter 'Scale script'. Or you can use your own script written in another programming language.