You have two types of memory on your computer, RAM memory (the main computer memory) and hard disk memory.
As rojash says, your pictures are held on hard disk memory not in RAM.
The ONLY things stored in RAM are programs that are currently running, such as Windows, and any applications you start (like paint shop pro or Internet Explorer).
If you close down any application like paint shop pro it is deleted from RAM.
When you shut down your PC EVERYTHING is removed from RAM.
What memory are you short of, RAM or hard disk ?
It is fairly easily to increase the amount of both on your computer.