how to get pictures from my computer to the iphone, that are not in a backup?

Okay.. so I am having problems with my iphone4 and I want to try resetting it back to Factory Settings to see if that will help, I have written down all of my contacts so I won't lose them.. but i do not want to lose my pictures. I have done a backup just in case.. but I don't want to use the backup since that would be just useless.. because i will most likely be putting whatever issue the phone is having right back into it. So I want to know if there's a way i can get the pics that i have saved on my computer now, back into the iphone WITHOUT using the backup. Please and thanks!