I was having a discussion with someone the other day about the risks of posting photos online, and their view was that if you put something online you deserve to have it stolen and used without your approval. Especially if you post large resolution images, and doubly so if you don't use a watermark.
I was reminded of a quote, which I completely agree with, from Zak Arias ( http://dedpxl.com/ ) that went something along the lines of:
Posting photos online is a lot like fishing.
Let me explain:
You throw your bait out there for the world to see, in the hope you get a "big fish" to grab onto your line and you can reel them in. You don't get huffy when a fish steals the bait but doesn't take the hook. This just confirms that there are fish out there to catch. Instead you put more bait on and cast your line in again.
You don't put protection around the bait so it can't be stolen because this will alert the fish to the fact that it is not real, and you don't pull up all your hooks and go home when you lose your first piece of bait.
I know that my photos get 'stolen', and generally I am not too worried about it. The people who screen grab an image and put it on their desktop background or use it for their local school newsletter are not likely to be in a position to pay for the rights to use the image, even if they are aware that they should. I don't sweat the small stuff.
That said, when I see a big fish stealing my work and using it for commercial purposes, when I know they know better, I am happy to chase them down, even if it means they will never come back to me for images again.
And there are people/companies out there who are happy to purchase images when they need them, and I am always happy to help them out.
So I continue to post my work on the internet, high quality with no watermark , because I know that even though I may not have sold many images, I have sold a lot more than if they had been sitting on my hard drive where no-one else can see them.
I will keep fishing.