if i make a wallpaper admin page,
i create folders with category names in a temp folder.
you can upload the wallpapers with all the sizes,
then on admin page i have a button:
sync categories.
this program then insert those wallpaper names into the database (using the categories where they stored for this process) which aren't already in, then the uploaded files will be deleted and moved into a "live" folder.
on insert a timestamp is generated, so i can list them as new images.
next time use talketive title to your questions.