You mean cropping the watermark, which contains a copyright notice. You can no more crop the copyright than you can breathe with no lungs.
Cut and dried is actually easier to prove than you think, even when a photo's been cropped. The pixels in the image that correspond to the original will be identical in the copy, unless some modification took place. The metadata is another place that some people are sloppy about editing. Most smartphones and some dSLRs will leave a GPS location/time stamp in the metadata, as well as including info about the camera hardware and its settings. It's easy enough to identify the owner in cases where the metadata wasn't edited.
I don't see a watermark and copyright mark necessarily as the same thing. A watermark to me is any type of transparent mark on an image or design that attempts to discourage theft or make the image or design unusable if stolen. At times the watermark and copyright are one in the same. I know many editing tools that call the fuction of applying a mark, a watermark. A copyright mark is simply "©". Most times accompanied by year and name, putting the public on notice usually found in a corner of an image or more commonly the bottom of a website. The way "I would us" a copyright mark is not to prevent use by others but to credit the creator/owner. One is more effective at discouraging image theft while at the same time sacrificing image quality. They are not necessary the same thing, although they can be. I understand you don't need to put a copyright on an image for it to have copyright.
Legally you can't crop the mark but It happens. If your going to steal such a photo your already in the wrong, cropping it off is foregone conclusion at that point. The legal threshold has been crossed, not much stopping someone ethically from cropping it also. My point was more about what Alex's intention for using the photo was. As explained in Alex's email, I believe Alex thought he was helping Anthony (free advertisement), at the same time satisfying his need. Had it been intentional theft, Alex might have attempted to crop it instead of leaving the mark on for the whole world to see. Making the theft obvious to all, not just its creator.
Metadata can be removed a few ways, which I will not explain here.
I also think Alex did not understand the difference between use on a website and use on social media. I believe (you can look this up, I don't have time) because of the user agreement on sites like Facebook and Twitter, the creator of a photo gives up copyright by posting it there. Allowing followers to re-pin-post-tweet the image. If it was on social media before Alex took it, does that release copyright for use on one's own website (commercial or otherwise)? I don't know. (you can look that up for me)
I prefer we not use specific jargon regarding editing and photography. I'm not here to educate anyone or provide information to those reading that didn't require any discipline to attain it. There are many resourses people can use before we get too technical moving forward.
So, if I shoot you walking on the street and include you in my motion picture without obtaining a model release from you, I can simply say, "oh, but I gave you exposure."? No. What if such exposure isn't desired? What if I used that footage of you in a porn film? What if I used it in a commercially-sold religious video and you don't believe in that religion, or worse, its beliefs are antithetical to your own?
As owner of the copyright, Anthony has the right to determine how and in what context his work can or can't be used for any purpose not covered by Fair Use Doctrine.
The image was used briefly in a message about a limited-time offer - it's unlikely that the image owned by Tony would have been used again, nor is there any guarantee that Alex would have "thrown him a bone." BTW: as far as your livelihood goes, do you prefer getting fair and just legal compensation for your work, or do you prefer that you occasionally get thrown a bone?
I never said he does not have the right. I'm saying the value of getting exposure from the right people is worth more "to me" then the cost of one image. Anthony is in the business of reporting playing card news. Someone (Alex) who's website and company are well known by all in this industry makes a mistake and uses a photo that has Anthony's watermark on it. I'm not going to nail Alex to the wall or post private emails. Especially if the subject of the photo is a product of that company.
There are other examples that I would inforce copyright, which I will not explain here.