How much secure this will be ? My concern is what if some one show my digital photo to the website, will framework detect it ? Apple said that they over come

How much secure this will be ? My concern is what if some one show my digital photo to the website, will framework detect it ? Apple said that they over come this by using true depth technology (which i guess required specific hardware). I like the idea thought, but there is a big reason people did not implemented this before.