Hi eabeukes,
In the current version, Dotnetgallery saves two files after image uploading,
1. The thumbnail file, it is 128 pixels width by default, the height of the thumbnail file is calculated automatically based on the original file
2. The original image file
if you want to create a resized image(1024*768),
you need to get the source code and modify it to meet your requirements
Regards,
Jeff