Abstract: Previous historical and philological commentaries on Nostradamus' Prophecies by Prof. Brind'Amour, R. Prevost, P. Guinard, A. Penzensky, and D. Crouzet have led to the unexpected conclusion that many quatrains are uninformative as predictions; moreover, some of them describe events preceding the moment of publication, raising questions about the predictor's motivation. Against the background of the increased interest in the development of cryptology methods in the first half of the sixteenth century, it is appropriate to assume the existence of a hidden message in the Prophecies. Recent work by the author has shown that the text of the Prophecies contains two types of cipher. The modified algorithm "scytale" is used to change the sequence of quatrains and assign them specific dates in real time. Additionally, a sizeable graphical cipher is invisibly embedded in the text so that particular words or letters, mapped as stains on a plane in the coordinates "century number” or “quatrain number," lead to images of human faces. These images likely serve as illustrations of the prophetic text; however, their low quality and the cipher author's tendency toward surrealism make it challenging to identify the characters. This work proposes a new method for processing the raw data to obtain higher-quality images, called the "smooth assembly" method, and to discuss Nostradamus' graphical cipher in a historical context. The study's results suggest that Nostradamus' graphical cipher was a unique experiment in embedding images in text and had significant scientific value for developing steganography in the sixteenth century. This leads to the assumption that, in addition to predictive motivation (or instead of it), the cipher author pursued a purely scientific goal: creating a new promising method of covert information transmission.