Photo metadata possible in analog print?

Question

A friend of mine had his passport photos rejected by a consulate on the grounds that they could "detect" that the photos were old. They did not see him in person, since the application was sent by mail.

The photos were printed at Walgreen's or CVS, and are about a year old. There was no discernible difference in his appearance between these photos and the photo in his passport.

This confuses me because the only way I can think of that would transfer any info of that sort to an analog print is embedding the date that the photograph was taken (accessed from the metadata), and including that on the code on the back of the print.

Am I missing something? Is is possible to embed metadata in an analog print?

Answer 1

Is is possible to embed metadata in an analog print?

Not only is it possible, it's pretty much certain that every page printed by every laser printer available from every major manufacturer prints at least the following information within the printed image:

• Printer model number
• Printer serial number
• Print date and time

This digital watermark is known as a Machine Identification Code (MIC), and has been around for decades. It is also known as a "yellow dot code" because it uses a grid or constellation of yellow dots, which are very difficult to distinguish under normal viewing conditions. The dots encode around 64 bytes of information within a few square centimeters, and are repeated across a printed page (allowing for information recovery even from a partial printed page). The original purpose of the MIC watermark was to provide a method for government authorities to identify counterfeiters who used increasingly available and inexpensive printers to print funny money. Xerox researched, developed, and patented the technology.

From this Electronic Frontier Foundation (EFF) list of laser printers known to employ some sort of tracking code (whether by yellow dots or other means),

(added 2017) Reminder: It appears likely that all recent commercial color laser printers print some kind of forensic tracking codes, not necessarily using yellow dots. This is true whether or not those codes are visible to the eye and whether or not the printer models are listed here. This also includes the printers that are listed here as not producing yellow dots.

(Note that the list is no longer being updated, as it is assumed that all color laser printers use some sort of forensic tracking codes).

The investigation and arrest of Reality Winner for her 2017 NSA leak was reported to have been enabled by the use of MIC printer codes. The codes probably weren't necessary (enough other forensic information was more readily available (IT logs)), but some of the specific details of the printed document's code has been reported.

Answer 2

The prints you describe are likely not "analog". They are digitally printed via laser or LED on photographic paper. From your question, it's not clear when the photos you describe were printed. (Are they old photos that were printed a year ago or old photos printed recently?)

• If the photos were recently printed, the date the photos were actually taken may be printed on the back of the photo.

• If they were printed a year ago, it's possible they contain a code that identifies the printer, date, and other characteristics. For instance, color laser printers place little yellow dots throughout the page to encode identifying information. (Scottbb discusses this in more detail.) Currency also has similarly encoded information to prevent counterfeiting.

  I have encountered non-laser-printed photographs containing numerous yellow dots in white backgrounds, such as those which are common in passport photos. To see whether this is the case, examine the print with a magnifying glass under blue light.

• Another possibility is, they "detected" that he was re-using photographs he had previously used, since you state, "There was no discernible difference in his appearance between these photos and the photo in his passport."

• He also may not have shown the expected amount of aging. It doesn't matter how well people age, they will look different after a decade (in the US). However, Canadians basically live in a refrigerator, so they look younger and live longer.