Imagine that whenever you took a screenshot the text “TAKEN ON AUSTINJP’S IPHONE” were written across the page.
A “watermark” is simply a version of that designed to be invisible or imperceptible to the human eye, for example by embedding information in the least significant bits of the pixel colors.
“Digital Watermark Steganography” is a good search term for further investigation. As is the case with many security topics, there is an ongoing arms race between technology used to hide information, and technology used to detect information hiding.
At the end of the day if you truly wanted to share a screenshot of the iOS settings UI and remain anonymous, you should probably consider just drawing it with crayons. Except then someone will come along and process the crayon marks to recover your fingerprints etc. etc.
>A “watermark” is simply a version of that designed to be invisible or imperceptible to the human eye, for example by embedding information in the least significant bits of the pixel colors.
In this case however, it's hard to imagine how you'd do this without being detected. If you loaded the screenshot into mspaint and used the paint bucket tool, any color differences will become apparent. You could limit your modification to the edges, but detail there is going to get wiped by jpeg compression (if any).
A “watermark” is simply a version of that designed to be invisible or imperceptible to the human eye, for example by embedding information in the least significant bits of the pixel colors.
“Digital Watermark Steganography” is a good search term for further investigation. As is the case with many security topics, there is an ongoing arms race between technology used to hide information, and technology used to detect information hiding.
At the end of the day if you truly wanted to share a screenshot of the iOS settings UI and remain anonymous, you should probably consider just drawing it with crayons. Except then someone will come along and process the crayon marks to recover your fingerprints etc. etc.