This need to be done on a Linux machine
this we will need to use the Linux terminal
Create a folder called backup by running mkdir backup them move in ti this folder by running cd backup
now we need to grab the script that will shrink the image we will be creating shortly
with your SD card plugged in run df -h then plug in your SD and notice the difference you should see an entry starting /dev/sd we need to make a note of this in the example I will be using it will be /dev/udb1
we ned to run the foloowing commands
sudo dd if=/dev/sdc of=SDCardBackup.img