A QR code? What did you have in mind for interaction?
As far as I know you'd need at least two devices (the one whose screen is displaying the image with the QR code, and the one you're using to snap a photo of it). And then you'd probably want send the decoded URL back to the original device to load in the original browser.
Edit: Maybe you were thinking about the analog world, but watermarked images tend to show up in the digital space (in mockups especially).
As far as I know you'd need at least two devices (the one whose screen is displaying the image with the QR code, and the one you're using to snap a photo of it). And then you'd probably want send the decoded URL back to the original device to load in the original browser.
Edit: Maybe you were thinking about the analog world, but watermarked images tend to show up in the digital space (in mockups especially).