Consider this hypothetical situation: 1. User selects image. 2. User realises that they selected "Screenshot of Online Receipt" instead of "Photograph of Cat". 3. Website code has access to "Screenshot of Online Receipt". 4. User thinks, "Phew! At least I didn't click the Upload button!" 5. User changes selection to "Photograph of Cat". 6. User uploads "Photograph of Cat". 7. Website has access to both "Screenshot of Online Receipt" and "Photograph of Cat". Despite this, what you are asking for is possible. Using a URL, you could either modify it to access URLs selected elsewhere, or not access it at all; the URL is just a string and you can't tell where a string came from. You can, however, use a Blob or Data URI, because both of these are identifiable; the Blob is a direct reference to the file and the Data URI contains its contents. See: http://stackoverflow.com/q/20950791/5223757.