No Users on my MacBook Pro
You can backup your photos by entering in Single User Mode and then :


Steps


type mount -uw /

Then type du -h /Users/home directory/Picturesby this you can find out the space taken by your photos.(If you don't know the name of your home directory type ls -la /Users

Then plug in another pen drive larger than the size of the photos

Then type mkdir /usb

Then type mount -t [filesystem of pen drive] /dev/diskX /usb (X will be your disk identifier

then Press enter and type rsync -p -o -P /Users/homedirectoryname/Pictures /usb

After the copying process is over type shutdown -h now

This will copy  your entire photos library which you can open on another mac.