It's been in widespread use for decades. Back in the 90s there was Digimarc who inserted copyright details into photos and video by changing the shading of pixe

It's been in widespread use for decades. Back in the 90s there was Digimarc who inserted copyright details into photos and video by changing the shading of pixels in an unnoticeable pattern, and they even said the method could be applied to car paint. All you need is a high resolution scanner, and given that the cameras on your typical game console are high enough to see skin temperature variances and determine one's emotional state (best in combination with galvanic skin response), the scanners are everywhere. Think about that the next time someone complains about data tracking.