The first thing I can say is never upload up original image files on the Internet.. make it small...and then you put it up... but in internet you can not 100 % all photos protect.
And if I know correctly, then here in steemit is a program...made by users...if your photo come up on many pages ... then this photos get fast comments that it is up here more then just one pages..... and this post maker must make so that it would show where it comes from ... or this post start get lot flags .
And if your photos are very good, then you need to use a watermark.