Question: Copyright for Artists FAQ: How Can I Protect Photos of My Paintings?
Answer:
If you put photos of your paintings on your website, at some stage someone is going to use them without your permission (or if you're feeling aggrieved, 'steal' them). So what can you to do limit the damage?
Start by only putting up low-resolution versions of your photos, and at as small a size as possible. Save your photos in whatever photo editing software you're using as 72 dpi; you don't need a higher resolution for the web. Then resize them to as small a size as will work for your website design ... but not so small that users can't see the paintings. Low-quality photos can be copied onto other websites, but aren't good for printing out.
Consider adding a watermark to a photo. That's where you put your name across the photo is a semi-transparent color. It is possible to remove a watermark, but most people won't spend the time doing so.
Adding a 'no right click' function to your website prevents people from right-clicking on a mouse to save the photo. But it's very annoying from a user's point of view as it also stops you from using the other options on the menu, such as right-clicking to open a link in a new window, which I use a lot. Rather consider setting things up so that people save a different image to the one they see, known as shrinkwrapping.
Ultimately there is only one way to ensure that a photo of a painting isn't copied: don't put it on your website in the first place.
If you want people to be able to use some of your material, or in specific ways only (such as non-commercial or no derivatives), investigate the Creative Commons range of copyright licenses which sets it out in clear, unambiguous language that only an idiot would try to argue they didn't understand.
Disclaimer: The information given here is based on US copyright law and is given for guidance only; you're advised to consult a copyright lawyer on copyright issues.
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