Virtual Unfolding- Can You Read A Letter Without Opening It?

by Kareena Dodeja
Virtual Unfolding- Can You Read A Letter Without Opening It?

March 8, 2021

Letters were perhaps the most affectioning and worthwhile medium of communication. Even today, nothing beats a handwritten note or a postcard from a friend vacationing at an exotic location. However, what if we told you that there is a technology which can read the text without opening the letter called virtual unfolding! Intriguing? Let's find out!

Three hundred years ago, letters were the way of communication between people. They spilled their thoughts on paper not on Facebook statuses, feeling old right? There was a technique called Letter Locking where they would fold the flat sheet of paper to become an envelope. It sounds unreal but during that time letter locking was the protect your message not passwords like today.

The team of scholars read the letter from early 17th century Europe without damaging the letter, what? The team included MIT Libraries and Computer Science and Artificial Intelligence Laboratory (CSAIL) researchers and students. It was titled ‘Unlocking history through the automated virtual unfolding of sealed documents imaged by X-ray microtomography.

The research was published in the journal, Natural Communications. Virtually unfolding is to read the letter’s contents but not opening it in any way. The research team in a statement said that the algorithm could take us right to the heart of the letter without physically opening it. They said that using virtual unfolding to read a story that never reached the recipient is truly extraordinary.

The team at CSAIL discovered a way to virtually unfold a letter.

Got a secret? Lock it Up

Letter locking is a historical process since the paper’s folds are valuable evidence for historians. They are a team of researchers who developed this process as a field of study at King’s College London. Jana Dombrigo, one of the researchers explained that letter locking was an everyday activity for centuries across cultures and there is a lot of moral ground associated with it. This research could help them find the missing link between the ancient world and modern cryptography. This method was used to secure written communication in the 1830s; this was adopted by historical figures such as Queen Elizabeth I of England writing to Marie Antoinette.

Between 1689 and 1706, around 577 locked letters were delivered to The Hague in the Netherlands, these letters were found in a trunk of undelivered mail. The letters were never reached to who they were written for. A team found a way to read the letters without breaking the seal or unfolding it. They used a sensitive X-ray scanner and computer algorithms to virtually unfold the letter. They thought they could simply cut these letters open but they learned that the letters could provide them some revealing information about the past; they were inquisitive about what could be inside the letters.

Between 1689 and 1706, 577 locked letters were sent which can be only unlocked virtually by X Rays and computer algorithms.

Virtual unfolding was developed by Amanda Ghassaei SM’17 and Holly Jackson, an electrical engineering student and computer science student at MIT. Ghassaei revealed in a statement that sealed letters intrigued them and they found it interesting because of the attention paid to sealing them shut. David Mills explained they used computational flattening algorithms to scan the letters. They had successfully opened books and documents with one or two folds but the intricate folding of some letters could pose some challenges.

The team used 2D and 3D geometric analysis to understand the folded and flat states of the letters as well as the crease patterns. They studied 250,000 historical letters then devised a format to look over the details such as slits, locks, and creases.

Virtual Unfolding - How did it all start?

The X-ray scanners were built to map the mineral content of teeth and were mainly used for dental research. It proved handy to the research to scan the letters. David Mills, the author of the study in a statement said that this scanning technology is similar to a medical CT scan. It has intense X-rays which allow us to see the traces of metal in the ink used to write the letters. They scanned the images and turned them into letters so they could virtually open them up and read. 

The letter was dated back to July 31, 1697, from Jacques Sennacques to his cousin Pierre La Pers, a French merchant in The Hague for a request regarding a copy of the death certificate of Daniel Le Pers. The letter was written in French and translated to English for the study. The researchers have found there are wormholes in the paper as they found there is missing text in it. The letters give an insight into the lives of the people during that era and their daily life details. 


The researchers did a little more digging and found that Sennacques is a legal professional in Lille who requires the death certificate in the question of inheritance. They found the letters in a trunk of a postmaster known as Simon De Brienne and his wife, Marie Germain. The Museum Voor Communicate acquired these letters in 1926. The trunk was filled with 2,571 opened letters as well that never reached the recipients. 

During that time, there were no postal stamps so postage stamps so the postmaster had to deliver the letters by themselves. We can now connect to the past through technological inventions, it is extraordinary.


Recommended for you

Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More