Like the previous post, this post riffs on a photo  I stumbled on while looking for something else.
Would it be easier to identify the man in this photo or the man whose photo appeared in the previous post, copied below.
I think it would be easier for a human to recognize the person in the first image. But what about a computer?
We humans identify people most easily by their faces, and especially by their eyes. These features are easier to see in the first photo. But what might we find if we applied some image processing to the two photos? Maybe the green man’s facial features could be exposed by some diligent processing. We see more of the second man’s body. Maybe a computer algorithm could extract more information out of the second image for this reason.
Photographs may, and often do, contain Exif (Exchangeable image file format) metadata, such as the GPS coordinates of the camera at the time the photo was taken. A photo taken when the lens cap on by mistake might contain a good deal of information about the subject even though the photo per se is useless. This information can be useful to the photographer, but it could also pose a privacy risk. Before posting a photo publicly, you might want to strip out the metadata.
As I noted in the previous post, the privacy risk from data depends on context. Suppose the metadata embedded in a photo contains the serial number of the camera. That serial number would not help most people identify a photo(grapher), but it would someone who had access to a database linking serial numbers to the customers who purchased the cameras.
Was the first photo created by actually projecting the red and green lights onto the subject, or were these added in post production? For that matter, was there actually a man who posed for the photo or was the image synthetically generated? A forensic investigation of the photo might be able to answer these questions.
 Photo by Sebastian Mark on Unsplash