Thank you for your answer tschommer, the wallpapers are probably not stored in any of the /home folder, i did a search and didn't find anything.
While i was searching for the folder containing all the wallpapers that i add in Folder View Settings i went to /root/temp/kdecache-bluesman/plasma-wallpapers/home/bluesman/wallpapers/My wallpapers and there they are, all of them in 2 different sizes the first being 164 x 102 and the second size is 1280 x 800 so i believe that i find what i was looking for.
I wanted to backup this particular folder, hoping this is the one use for Folder View Settings to put the wallpapers on the desktop so that i don't have to do it again because i actually have more than 160 wallpapers that i want to save and there is going to be more later on....
I hope this is the right folder to save but if it's not please don't hesitate to let me know
and thanks again for your time.