Windows 10 image-ATI 2014

I have some numbers I would like to offer and get your reaction to whether or not I am doing this right.  The size of my C drive is 46.9GB.  The size of the image I created shows up as 34.2GB on the Tree size Free app using High pressure shrinkage....but when I check the size of the image on windows it says it is only 19GB.  I am concerned that it is so much smaller I might not have a reliable image with which to restore in the event of a jproblem.  Do these numbers seem reasonable and do you think I am safe to use the image to test the recovery capability.  I know without other information you cannot be certain but what is your best guess.  BTW:  I didn't include hiberfil.sys and pagefile.sys on the image.        -C. Brawner