Depends on where you upload. At Alamy you will need model releases.  This might be accepted elsewhere, but different inspectors have different opinions.  I had a silhouette rejected on Stock once because they said if you can adjust the image enough and see facial features it won't bee accepted. I mean, you would have had to drag sliders dramatically enough that the image quality would not be worth using.  But its their company, not mine. It is one of my better sellers on other micros.