I think the question is why would we need protective watermark anyway if stock photo companies are already crawling and sometimes phishing for use of licensed stock photography on the web and then directly send out an DCMA or a charge?
I've been in many situations where the copyright owners reached out for damage fees after downloading a full-res, un-watermarked photo from free stock photos sites in blog posts, so I'm sure the tech is all there already.
What if you put it into a video? Photoshop it into a meme? Drop it in to an internal presentation?
These are all situations where the copyright of a stock image owner is infringed and yet there is very little that automated processes can do to detect them.
If I put a copyrighted image into an internal presentation, I am still copying and redistributing this image. Without permission to do so, that seems like it's straight-up infringement. I don't believe it usually meets the criteria for fair use, either.
Sure, I do that all the time. But, two things to consider:
1) No one outside of the 5 people attending the presentation will ever know. The 5 colleagues following the presentation absolutely don't care where the images are coming from, as long as the point is clear and I'm speaking loud enough.
2) Redistributing ? Really ? If I'm sending a cat picture to my mom, my manager or my favorite slack channel, I'm "redistributing" ? Come on. It's not a publicly available blog post, it's my inner social circle.
I'm never going to pay $30 for the few images I used to make my presentation less boring. However, I can make a little effort and put a 12pt "credits" slide at the end (usually, no one care about).
a. Copyright isn't about audience, it's about author. Ask if the person whose work your using would care, not the people seeing it
b. copying is copying every time, not just after the n-th time
c. credit acknowledgement is good, but it doesn't pay the rent for people who work to create content
d. a rough rule of thumb would be whether you're using art to support a profit motive. Anything that happens for your work would be considered in support of a profit motive.
e. "ask" in point a is not used in the figurative sense
I've been in many situations where the copyright owners reached out for damage fees after downloading a full-res, un-watermarked photo from free stock photos sites in blog posts, so I'm sure the tech is all there already.